oral cavity - mgumst.org
TRANSCRIPT
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1
By
Dr Shikha Dhal
Oral cavity
Read pages 891-898 perez,Subsites
1. Lip
2. Buccal mucosa
3. Lower alveolus
4. Retromolar trigone
5. Oral tongue
6. Floor of mouth
7. Upper alveolus
8. Hard palate
Management
Diagnosis
Treatment
Surgery
Surgery preferred over
radiotherapy as a single
modality
Assessment of
Unresectability
1. Lesions involving or close to bone: to prevent radionecrosis.
2. Site where surgery is not functionally & cosmetically morbid.
3. Young patients: p/o a subsequent second primary.
4. Presence of SMF
1. Gross extension to skull base:Erosion of pterygoidplates, sphenoid bone, widening of foramen ovale.
2. Encasement if ICA> 270 degrees and clinically fixed nodes.
3. Involvement of mediastinalstructures, prevertebralfascia or cervical vertebrae.
Principles of resection1. Enbloc resection of primary tumor whenever possible.
2. In continuity neck dissection when direct extension of primary into neck.
3. Third dimension ( the base) is taken carefully into account before excision, because, as the thickness increases so does the risk of regional metastases & the need for adjuvant elective neck dissection in oral cavity cancers.
4. Adequate margin to obtain clear FS & permanent margin:1.5-2 cm ,clear margin:> 0.5 cm,closemargin:< 0.5 cm
5. FS confirmation for margins may be done if facilitiy is available: LVI cannot be assessed on FS.
6. If perineural invasion is suspected ,the nerve should be dissected both proximally and distally & resected to obtain clearance of disease.
7. C/L neck can be addressed : when p/o B/L ( palate,tongue) C/L metastases is high, tumor crossing midline( ant .tongue & FOM)/midline tumors.
8. Elective neck treatment is often used for management of the clinically node negative patient with oral cancer, and therapeutic neck dissections are performed for patients with clinically apparent nodal disease .Because of the high occult metastatic rate for many cancers, elective neck treatment is encouraged in all but the earliest stages of primary site disease.
N0: Selective neck dissection: for oral cavity:SOHND, I-III
N1-N2a-c:selective or comprehensive neck dissection.
N3: comprehensive neck dissection.
Contd..
Surgical approaches to cancers of the oral cavity may: transoral, transcervical (pull-through), or alternatively, via mandibulectomy, which is sometimes necessary to obtain the exposure required to achieve adequate margins.
In cases where the mental or alveolar nerve is involved with tumor, the nerve should be proximally resected and analyzed microscopically.
A tracheotomy is often necessary to maintain a patent airway because of the large amount of oral edema resulting from extensive resection and placement of myocutaneous flaps in the oral cavity.
Contd..
Tumors that approximate the gingiva should be resected with the gingiva and periosteum as an additional deep margin, while those that appear to involve the periosteum should be resected with an additional deep margin of bone. This last procedure is termed a marginal mandibulectomy.
Depending on the extent of tumor involvement, this may involve resection of a bicortical rim of bone at the upper aspect of the alveolus (rim mandibulectomy), or alternatively selective removal of the inner cortex using a vertical or oblique resection (sagittalmandibulectomy). It is commonly recommended to leave at least a 1-cm thick segment of bone inferiorly following a rim mandibulectomy to reduce the risk of pathologic fracture.
Those lesions that directly invade bone should be resected with a segment of bone. This often requires soft-tissue or osseous reconstruction of the resected bone segment.
Reconstruction 1. Mucosal defects: small defects :primary closure/local flap/SSG;
large defects : primary closure, skin graft, local flap (intraoral defects reconstruction with palatal, tongue, and buccal mucosa flaps but usually at the cost of decreased function), regional flap(pectoralis major flap, trapezius flap, and latissimus dorsiflap) /or free tissue transfer ( the radial forearm flap,theanterolateral thigh flap, the rectus abdominis flap, and the fibula flap) from different sites.
2. Soft tissue loss:( pedicled flaps eg. PMMC) or free tissue transfer
3. Skeletal defects +/- soft tissue & skin loss: free fibula/deep circumflex iliac artery, regional osteomyocutaneous flaps, plate, PMMC.
4. Skin defects: local flaps/ forehead flaps, deltopectoral flaps/ PMMC, free flaps.
Total glossectomy defects are well suited for free flap
reconstruction. Reconstruction of the mandible often
requires free flaps that contain bone and soft tissue such as
the fibula flap, the iliac crest flap, and the scapular flap.
Compared to reconstruction plates free flaps also allow the
potential for a sensate flap through neural anastomosis. A
sensate flap may result in improved swallowing and speech
function, but few studies have unequivocally demonstrated an
improvement in these functional outcomes.
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2
Radiotherapy is preferred over surgery as a single modality
Severe impairment of function & cosmesis with surgery.
Comorbidity
For early ( T1, few T2) lip, oral tongue, and floor of the
mouth tumors, radiation therapy is an effective means of
securing tumor control. Acceptable control rates have been
achieved with brachytherapy alone or with a combination of
brachytherapy and external beam radiation. Early work
indicates that the success rate of radiotherapy is higher if
some or all of the treatment is administered with
brachytherapy .
Radiation therapy in advanced oral cavity cancers ( stage
T3 &T4) can be delivered preoperatively or postoperatively.
Disadvantages of
preoperative radiation
therapy
Advantages Postoperative
radiation treatment
a delay in definitive
surgical treatment.
limits the dose of radiation
that can be delivered due
to the risk of wound
complications after
surgery.
no dose limitation.
no delay in the
implementation of surgical
resection.
Gives a complete
pathologic staging of the
tumor.
Indications
Postoperative Radiotherapy Brachytherapy
1. Primary:
large primary:T3/T4
positive or close margins
deep infitrative tumor
high grade tumor
LVI & PNI
suspicion of mandibular cortical
involvement.
2. Lymph node:
bulky nodal disease:N2/N3
Extranodal extension
Multiple level involvement
Multiple nodes
1. Accessible lesions.
2. Small ( preferably <3 cm) tumors.
3. Lesions away from bone.
4. N0 nodal status.
5. Superficial lesions.
6. Favourable histology
7. Proliferative or ulcerative lesions.
EORTC 22931:( Bernier et al. 2004): 334 pts with operable stage III/IV oral cavity, oropharynx, larynx & hypopharynx randomized to postop RT( 2/66Gy) vs postop CRT (2/66G y & cisplatin 100 mg/m2 on days 1,22,43).All pts received 54 Gy to the low risk neck. Eligible stages: pT3-4N0/+,T1-2N2-3 & T1-2N0-1 with ECE, positive margins, or PNI.
This study demonstrated a benefit in locoregional control and disease-free survival for the chemoradiation arm, but no overall survival benefit was appreciated.
ARM 5Y PFS (%) 5Y OS (%) LRR (%) GrIII
toxicity
(%)
Sx→RT 36 40 31 21
Sx→ CTRT 47 (p=0.04) 53 (p=0.02) 18 (p=0.007) 41 (p=0.001)
RTOG 95 01(Cooper et al. 2004): 459 pts with operable oral cavity,
oropharynx, larynx or hypopharynx who had ≥2 involved odes. ECE
or a positive margin to postop RT(2/66Gy) vs postop chemoRT
(2/66Gy & cisplatin 100 mg/m2 three wkly).
ChemoRT.Postoperative concurrent administration of high-dose
cisplatin with radiotherapy is more efficacious than radiotherapy alone
in patients with locally advanced head and neck cancer and does not
cause an undue number of late complications.
Combined analysis(Bernier 2005):chemoRT improved OS, DFS, LRC
for ECE, &/or positive margin in stage III/IV,PNI,LVI, & / or
enlarged LN in levels IV-V for oral cavity & oropharynx tumors.
Patients with ≥2 LN without ECE did not benefit from chemo.
ARM LRC (%) DFS(%) OS(%) Ac. Toxicity
Gr III (%)
Sx→ RT 72 43 57 34
Sx→ CTRT 82
(p=Significan
t)
54
(p=0.04)
63
(p=NS)
77 (P<0.001)
The landmark studies of the Radiation Therapy Oncology Group (RTOG)
9501 and the European Organisation for Research and Treatment of Cancer
(EORTC) 22931, followed by the comparative analysis of Bernier and
colleagues, demonstrated that all patients with resected head and neck
cancer receiving standard fractionated postoperative radiation who are
found to have positive margins or extranodal extension should be assigned
to a combined chemoradiation approach using concurrent cisplatin (100
mg/m2 on days 1, 22, and 43).
More recently, the German Cancer Society 95-06 trial demonstrated that
even with hyperfractionated accelerated treatment regimens, patients that
received concurrent 5-FU and mitomycin experienced an improvement in
locoregional control and overall survival.
Finally, a study by Garden and colleagues examined patients with stage III
and IV disease who received a concomitant boost treatment regimen and
cisplatin on days 1 and 22, and found that 4-year locoregional progression-
free survival was 74% and that 4-year overall survival was 54%.Clearly, the
ideal chemotherapeutic regimen in the postoperative setting has not yet
been fully elucidated.
Chemotherapy and Radiation
The application of chemotherapy to the treatment of head and neck cancer dates back to the 1960s. There are a number of studies that demonstrate a benefit of concurrent chemotherapy administration in the definitive treatment of head and neck cancer with radiation. Although these trials vary with respect to radiation dose, fractionation schedule, and chemotherapy regimen, they have in common a randomized comparison between radiotherapy and radiotherapy plus chemotherapy. The advantage of concurrent chemotherapy with radiation has been further examined in the context of several meta-analyses. These meta-analyses generally identify a small overall survival benefit for the use of chemotherapy on the order of 1% to 8%. Summary analyses suggest no significant survival benefit for the use of neoadjuvantand adjuvant chemotherapy, but do suggest a clear benefit for the use of concurrent chemoradiation.
Posner et al. (NEJM 2007): randomized 501 pts with unresectable stage II-IV head & neck cancers( 14% oral cavity) to TPF ( docetaxol/cisplatin/5FU) vs PF (cisplatin/5FU) induction chemo f/b carboplatin chemoRT(70-74 Gy).Induction TPF improved LRC & 3 yr OS ( 48% to 62 % ),but DM.
Rose F. et al ( Asian Pacific J. cancer prevention): alternate schedule is as effective as standard three weekly schedule with respect to OS,LRC, time to local & systemic relapse rate.
Ho et al. demonstrated that 3 weekly schedule was less well tolerated than weekly schedule.
Several recent studies have focused on the use of chemoradiation in patients with high-risk pathologic features following initial surgery.
Cooper et al. reported the results of a randomized study in North America comparing radiation alone (60 to 66 Gy) to chemoradiation (same radiation dose plus three cycles of 100 mg/m2 cisplatin) in patients with head and neck carcinoma demonstrating high-risk features after gross total resection. High-risk disease was defined as any or all of the following: two or more involved lymph nodes, extracapsular extension of nodal disease, and microscopically involved resection margins. This study demonstrated a benefit in locoregional control and disease-free survival for the chemoradiation arm, but no overall survival benefit was appreciated.
A parallel study in Europe by Bernier et al. randomized patients to essentially equivalent treatment arms following head and neck cancer surgery. Eligibility criteria included patients with pathologic T3 or T4 disease (except T3/N0), or patients with any T-stage disease with two or more involved lymph nodes, or patients with T1-2 and N0-1 disease with unfavorable pathologic findings (extranodal spread, positive margins, perineural involvement, or vascular embolism). Local control, progression-free survival, and overall survival were superior for patients on the chemoradiation arm. These studies suggest that the addition of chemoradiation following surgery may be beneficial in selected patients with high-risk head and neck cancer, although with increased toxicity profiles.
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Trials of Adjuvant Radiation
Although surgery has emerged as the preferred initial treatment approach for the majority of patients with tumors of the oral cavity, adjuvant radiation is commonly recommended to enhance the likelihood of locoregional tumor control.
Robertson et al. conducted a phase III study in the United Kingdom of 350 patients with T2-4/N0-2 oral cavity or oropharyngeal cancers comparing surgery and postoperative radiation versus radiation alone. Because a difference in survival was identified, the study was closed early. The authors found that after 23 months, overall survival, cause-specific survival, and local control were all improved on the surgery plus radiation arm.
In regards to buccal mucosa cancers, Mishra et al. conducted a prospective randomized trial of surgery with or without adjuvant radiation 6 weeks after surgery. They reported a 30% absolute improvement in disease-free survival, although there was no difference in overall survival with the use of adjuvant radiation therapy.
Radiation Techniques
Carcinoma of the oral cavity has traditionally been treated with opposed lateral fields, using either two-dimensional or three-dimensional CT-based techniques.
During simulation and treatment patients are commonly immobilized with a thermoplastic mask. Patients are placed in supine position with a bite block (for oral tongue and floor of mouth cases) to depress the tongue away from the palate (Fig. 41.14); some institutions use a cork and tongue blade for this purpose. Reasons for tongue depressor or cork use:
To spare upper teeth, upper gingiva and soft palate and to stabilize the tongue in floor
of mouth, lower lip, retromolar trigone and tongue tumors. Tongue stabilization in other oral cavity tumors.
The involved lymph nodes, commissures of the lips, and any scars in postoperative patients are outlined with thin solder wires.
For patients with a short neck, the shoulders are depressed by having the patient pull on a tensioning device looped beneath the feet. Generally, the oral cavity tumor bed and upper echelon lymph nodes are included within the initial lateral fields (Fig. 41.15).
If a three-dimensional (3-D) plan is to be generated,
orthogonal films for the superior (oral cavity) volume are
taken and the supraclavicular-neck field is simulated. CT
scans are then taken in the treatment position with the mask
in place. If a 3-D plan is not used, opposing portals are
simulated. A 3-D plan should be used for all except simple
opposed-lateral fields.
Borders: The upper border of the field is positioned to provide a 1.5- to 2-cm border on
the tumor bed in an attempt to partially spare parotid glands and hard palate if
possible without compromising coverage of the tumor bed and regional
lymphatics.
The inferior border of the field resides at approximately the thyroid notch, just
above the true vocal cords.
.Anterior: 2 cm in front of primary tumor (usually in front of mandible).
The posterior border is set at the mid-vertebral body /Back of vertebral
corpuses level if level V nodal coverage is not required. The nodal volume
should include level Ia-Ib, II, and III. For patients with more advanced neck
disease or neck risk or positive level V lymph nodes, where the posterior chain
requires radiation, the initial fields should be set behind the C1 vertebral body
spinous process
Lymph node (+): back of vertebral spinous processes.
Lymph node (+): neck and supraclavicular field is also treated.
The portals are then reduced at approximately 45 Gy to spare high dose to the spinal cord.
If patients harbor cervical lymph node metastases, or high-risk disease, then the lower neck will also be treated. In this case, a single half-beam-blocked anteroposterior field is matched to the inferior border of the opposed lateral fields at the level of the thyroid notch. An anterior larynx block is used, which protects not only the central larynx from unnecessary radiation dose, but also protects against spinal cord overdose due to three-field overlap.
Conformal RT Fields :
CTV1: GTV + 1 cm
CTV2: level Ib, II, III lymphatics
PTV: CTV + 0.5–1 cm
Megavoltage beams with an energy range between 4 and 6 MV are most suitable for treatment of cancers involving the oral cavity. ( dmax:a maximum dose at about 1 to 1.5 cm below the skin surface).
Cobalt-60 (similar average energy to that from 4 MV linear accelerators) remains a very acceptable radiation delivery unit for cancers in this region owing to the small lateral separation distances in the head and neck area.
When higher energy beams are used, bolus material may be necessary to bring dose to the surface as required for tumors that extend to the skin. This is particularly important in patients with large volume nodal disease or extracapsular extension where adequate dosing of superficial tissues is required.
Tissue compensating filters should be used with opposed lateral fields when the variation of the separation is >3 cm. All fields should be treated daily and at least 5 treatment days per week.
Normal tissues that are in the field but need not be irradiated are shielded with either mounted lead blocks or multileaf collimators.
In recent years, there has been increasing use of intensity-modulated radiation therapy (IMRT) for the treatment of head and neck region tumors. With regard to oral cavity cancer, IMRT offers the opportunity to diminish normal tissue toxicities, including damage to major salivary glands (xerostomia) and to the mandible (osteoradionecrosis). Dosimetric analysis of radiation dose to the parotid glands with evaluation of resultant salivary function suggests that limiting mean parotid dose to <26 Gy is associated with improved postradiation salivary function.
Ideal candidates for IMRT include patients with T1-3 primary lesions with ≤ N2b neck disease.
IGRT has provided an opportunity to enhance daily treatment precision for IMRT delivery. Tomotherapy, which involves the helical delivery of intensity modulated radiation, enables a high degree of target conformality coupled with the capacity for diagnostic CT scanning, thereby allowing image guidance for adaptive radiotherapy and daily setup verification .
IMRT volumes:
GTV: clinical/ radiographic gross disease.
CTV 1: postop bed ,including 0.5-2cm margin on primary &/or nodal GTV.
CTV2: elective neck.
Individualized PTV’s are used for GTV,CTV1,CTV2 with margin
Simultaneous Integrated Boost Technique (“Dose painting”):
GTV: 70Gy/2.12 Gy/fx(definitive),
CTV1:postop bed/high risk areas 60-66 Gy/2Gy/fx
CTV2:54-59.4 Gy at 1.8 Gy/fx.
60 Gy in 2-Gy fractions to the uninvolved but high-risk regions, and 54 Gy in 1.8-Gy fractions to the low-risk region
Definitive RT
Conventional fractionation: 66- 74(nccn) ya70(book) Gy/2 Gy in 6-7 weeks.
Altered fractionation:
1. 6 fraction/ week acclerated; 66-74Gy to gross disease, 44-64 Gy to subclinical disease.
2. Concomittant boost acclerated RT: 72 Gy/6 weeks ( 1.8 Gy /fraction , large field; 1.5 Gy boost as second daily fraction during the last 12 treatment days.)
3. Hyperfractionation: 81.6 Gy/7 weeks (1.2 Gy/fraction, twice daily)
Concurrent chemoradiation:
Conventional fractionation: primary and gross adenopathy: 70 Gy ( 2 Gy/fraction) & uninvolved nodal station: 44-64(nccn) ya 45-50 Gy.
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Postoperative RT Preferred interval b/w resection & postoperative RT < 6 weeks.
Can be started as soon as wound healing is complete, usually within 2 to 3 weeks after surgery.
Primary: 60-66 Gy(2 Gy/fraction)
However, for close or positive microscopic margins or extracapsularnodal extension, a 4- to 6-Gy localized boost should be considered. If there is gross residual disease, either further surgical resection or focal boosting up to 70 Gy is advisable.
Neck: involved nodal station:60-66 Gy ( 2Gy/ fraction)
uninvolved nodal station: 44-64 Gy( nccn) ( 1.6-2Gy/fraction) ya50-54(perez)
Postoperative chemoradiation: concurrent single agent Cisplatin i.v. at 30 (check chemo book) mg/m2 weekly or 100 mg/m2 three weekly.
Altered Fractionation
It is well appreciated that head and neck tumors are rapidly proliferating. Intensified radiation fractionation schedules to counter rapid tumor cell repopulation as a means of improving outcome as hyperfractionation or accelerated fractionation should be considered for patients being treated with radiation alone, as this approach has been demonstrated to improve the likelihood of locoregional tumor control .
The Radiation Therapy Oncology Group's (RTOG 90-03) altered fractionation randomized trial comparing conventional fractionation to hyperfractionation, split-course, and concomitant boost technique demonstrated a significant improvement in disease-free survival for the hyperfractionation and concomitant boost arms . These altered fractionation regimens were associated with higher incidence of grade 3 or worse acute mucosal toxicity, but no significant difference in overall toxicity at 2 years following completion of treatment. However, oral cavity carcinoma constituted a minority of cases enrolled in these studies.
Tumors suitable for brachytherapy
T1-2N0: Radical BRT: 65-75(book) ya 60-70 ebm Gy low dose rate Ir192 or equivalent doses with fractionated high dose rate.
When definitive radiation is used for oral cavity cancer, boosting the primary tumor with either interstitial implantation, submental, or intraoral cone therapy can result in increased tumor control and decreased complications, particularly osteoradionecrosis .
T1-3 N0-1: EBRT:56-60 Gy/28-30 fraction/6 week
Boost BRT: LDR Ir192:15-20 Gy or HDR: 14Gy in fractions over 2 days(4-3-3-4Gy)
Brachytherapy
Brachytherapy has been used to boost the primary site in the oral cavity before or following external beam radiation (Fig. 41.18).
When brachytherapy is used as a sole treatment modality, doses of 65 to 75 Gy are commonly prescribed over 6 to 7 days for oral tongue , FOM & buccal mucosa. Traditionally, radiation has been delivered using low-dose rates of 0.4 to 0.6 Gy per hour to the target volume. However, there has been recent interest in high-dose rate and pulsed-dose rate techniques , although there is no compelling evidence that these techniques are superior to traditional low-dose rate radiation in the treatment of head and neck cancer. Many techniques for brachytherapy in the oral cavity have been described. Brachytherapy can be accomplished with either rigid cesium needles or with iridium-192 (192Ir) sources afterloaded into angiocaths. The most common technique is afterloading with 192Ir. Guide needles can be inserted either free-hand or with the aid of a custom template to help maintain optimal source spacing.
Radioactive isotopes that have been used in the past in interstitial radiotherapy of oral carcinomas include radium-226, cesium-137, gold-198, and tantalum-182. Iridium-192 used in the form of pins (epingles), wires, or seeds preloaded in a plastic ribbon have the advantage of being suitable for afterloading techniques, and thus is used commonly for temporary implants. Iodine-125 may be substituted and is the isotope of choice for permanent implants. The use of remote afterloading of iridium sources with high-dose rate (HDR) is replacing the use of hand-loaded seeds in ribbons in most institutions.
For oral tongue lesions, if a combination of external-beam radiotherapy and interstitial implant is considered, several series have reported on the importance of adequate interstitial implant dose. The total implant dose is correlated with local control. Those patients who received an external-beam dose less than 40 Gy along with a higher brachytherapy dose achieved higher local control rates than those who received a lower brachytherapy dose. If the patients have neck disease, surgery with or without postoperative radiotherapy is recommended over radiotherapy alone.
Depending on the size of the lesion a single plane, double plane, or volume implant can be used to cover the tumor with a 1-cm margin.
For tumors <1 cm in thickness, single plane implants are adequate.
Surface mold radiation can also be considered for small tumors <1 cm depth or superficial lesions of the lip, hard palate, lower gingiva, and floor of the mouth.
However, when lesions exceed 2.5 cm, it is difficult to avoid significant cold spots in the implant volume. For this reason, it is recommended that for lesions larger than 2.5 cm part of the treatment be given with external beam radiation to supplement the dose to the cold spots. In this setting, a combined treatment plan typically gives 50 Gy over 5 weeks with external beam radiation followed by 30 Gy with a brachytherapy implant.
As tumors get too close to the mandible or are large in volume, the risk of osteoradionecrosis increases.
Surface mold radiotherapy can be used as a primary
treatment for select initial or recurrent superficial lesions of
the hard palate, lower gingiva, and floor of the mouth. An
impression is usually made of the surface to be irradiated and
a mold in the form of a partial dental plate is made of dental
plaster. After distribution of radioactive isotopes has been
outlined, iridium seeds, wires, or tubes for HDR treatment
can be inserted into the predrilled holes or grooves in the
mold and sealed with dental plaster. Treatment can be carried
out on an outpatient basis with the patient wearing the
surface mold several hours a day, or the patient can be
admitted into the hospital and wear the surface mold for
most of the day except during mealtimes. HDR remote
afterloading with fractionated delivery may be used with
surface mold.
Trials of brachytherapy
Decroix and Ghossein reported outcomes in 602 patients
with cancer of the oral tongue treated with radium
implantation or implantation plus external beam radiation. In
this series, recurrence at the primary site or at the primary
site and neck was 14% and 22% for T1 and T2 lesions,
respectively.
The Royal Marsden Hospital reported local control rates of
90% at 5 years for T1 and T2 tumors treated with interstitial
radiation with or without external beam radiation
Pernot et al. reported local control rates of 96% for T1, 85%
for T2, and 64% for T3 lesions of the oral cavity treated with
brachytherapy and neck dissection. In this series, local
regional control rates were 83%, 70%, and 44%,
respectively. Retrospective studies suggest that control rates
at the primary site of early oral cavity lesions treated with
brachytherapy alone or a combination of brachytherapy plus
external beam radiation range from approximately 70% to
>95%. Involvement of the mandible is a contraindication to
definitive radiotherapy because it compromises control and
increases the risk of osteoradionecrosis.
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5
Intraoral Cone The intraoral cone is another delivery tool to enable boosting of
radiation dose to sites within the oral cavity while avoiding direct dose to the mandible (Fig. 41.20). This technique is generally best suited for anterior oral cavity lesions in edentulous patients. However, palatal arch sites can be targeted with the intraoral cone as well. Treatment with intraoral cone involves either 100 to 250 kilovolt (peak) (kvp) x-rays or electron beams in the 6 to 12 MeVrange.
Lesions up to 3 cm are amenable to treatment with intraoral cone as long as they are accessible. Intraoral cone therapy requires careful daily positioning and verification by the physician. For this purpose the device is equipped with a periscope to visualize the lesion. The cone abuts the mucosa and is centered directly over the lesion. Intraoral cone treatment should take place prior to external beam radiation so that the lesion can be adequately visualized. A major advantage of cone therapy is that it is highly focal to the tumor bed but noninvasive. Hence, when available, for suitable lesions, it may be preferred over brachytherapy.
Intraoral cone, like interstitial brachytherapy, is a localized
radiation therapy technique that has been used to boost the
dose to the primary tumor in the oral cavity. Institutions with
significant experience with this technique have reported
results that rival those obtained by interstitial brachytherapy .
Either technique for boosting the primary tumor has resulted
in improved outcomes compared to high-dose radiation
therapy alone . In general, external beam radiation therapy
followed by either technique is preferable over radiation
therapy alone.
The advantages of peroral radiotherapy over interstitial radiotherapy or external-beam radiotherapy in properly selected patients are as follows: (1) only a small volume is irradiated and salivary gland function is therefore preserved and late dental problems avoided, (2) no hospitalization or anesthetics are necessary, and (3) the risk of bone necrosis is minimal.
Peroral radiotherapy can also be used in combination with external-beam radiotherapy to deliver a boost dose to lesions that are marginally encompassed by an intraoral cone. The boost should be given before the external-beam treatment and is usually 21 to 27 Gy in 3-Gy fractions.
Dental Care
Prior to the initiation of head and neck radiation a careful oral and dental evaluation, including a panoramic radiograph, should be performed.
Dentition in poor condition should be identified and considered for extraction to minimize the subsequent risk of osteoradionecrosis.
Specifically, those teeth that will reside within the high-dose radiation volume that demonstrate significant periodontal disease, advanced caries, abscess formation, or are otherwise in a state of disrepair should be extracted.
In addition, impacted teeth, unopposed teeth, and teeth that could potentially oppose a segment of a resected jawbone should be considered for extraction if they are anticipated to reside within the high-dose radiation treatment volume.
Extraction of marginal teeth should also be considered in patients who are deemed unable to maintain adequate oral hygiene.
A gap of 2 wks b/w extraction & initiation of RT should be there to provide for healing.
Routine extraction of all teeth included in the irradiated volume is
not recommended. The only teeth removed are those that are
unsalvageable, likely to require extraction shortly after irradiation,
or potentially damaging to the surrounding tissues.
When tooth extraction is done before or after irradiation, the
underlying alveolar bone must be smoothed to allow primary
closure of the gingival tissues.
Antibiotics are used routinely as a prophylaxis against infection.
All patients are given dental prophylaxis with cleansing of their
teeth and instructed on oral hygiene.
Mouth irrigation with 1% sodium fluoride solution is started
during radiotherapy and continued permanently after radiotherapy
to minimize radiation caries.
Radiation can induce several chronic effects in the oral cavity that warrant routine surveillance. Radiation can impair bone healing and diminish the capacity for successful recovery following trauma or oral surgery. For this reason, elective oral surgical procedures including extractions must be very carefully considered after radiation. Escalation of dental caries deriving from xerostomia following radiation is well recognized (Fig. 41.21).
Radiation of the major salivary glands changes the nature of salivary secretions , which can increase the accumulation of plaque and debris, reduce salivary pH, and reduce the buffering ability of saliva. This creates an environment in the oral cavity, which predisposes patients to caries.
During a course of radiation to the oral cavity, simple techniques such as the use of custom molds to absorb electron backscatter can diminish hot-spot mucositis from dental fillings and improve treatment tolerance (Fig. 41.22). Attention to oral hygiene with frequent dental follow-up examinations and cleanings, daily fluoride therapy (Fig. 41.23), flossing, and brushing should be an integral component of the education and postradiation care of patients.
Prognostic and Predictive Factors
The most significant prognostic factor for outcome in oral cavity carcinoma is the presence of cervical metastases. In patients with positive cervical metastases the 5-year survival is reduced by approximately 50% from that in the absence of metastases . The prognosis diminishes further when patients harbor multiple levels of nodal involvement or extracapsularextension (ECE).
In a retrospective review, Myers et al. found that 5-year disease-specific and overall survival rates for pathologically N0 patients were 88% and 75%, respectively; these decreased to 65% and 50%, respectively, if patients were node positive but without evidence of ECE. Patients who were node positive with evidence of ECE had 5-year disease-specific and overall survival rates of 48% and 30%, respectively.
Tumor infiltration, depth of invasion, grade, location,
number & size of nodes, ECE, PNI, microvascular invasion
Oral cavity Lip
Stage 5 Yr. Relative
survival
I 69.5-73.5%
II 55.5-60.4%
III 41.8-47.3%
IV 40.3-33.6%
Stage 5 Yr. Relative
survival
I 86.5-92.7%
II 75.5-91.5%
III 39.8-69.8%
IV 34.2-60.1%
Several histopathologic factors in the primary lesion are
associated with adverse prognosis. Tumor thickness and depth
of invasion have been shown to confer a higher risk of
regional metastases . Perineural invasion has been correlated
with cervical lymph node metastases, extracapsular
extension, and diminished survival . Microvascular invasion
has also been correlated significantly with cervical lymph
node metastases . However, lymphatic invasion has not been
correlated significantly with cervical lymph node invasion.
The prognostic significance of grade has also been evaluated .
Because of the wide variation in pathologic interpretation, it
is difficult to discern the independent value of histologic
grading as a prognostic or predictive value .
.
6
Clinically detected nodal metastasis by T stageN0 % N1% N2-3%
Oral cavity
T1 86 10 4
T2 70 19 11
T3 52 16 31
T4 24 10 66
Floor Of Mouth
T1 89 9 2
T2 71 18 10
T3 66 20 24
T4 46 10 43
RMT
T1 88 2 9
T2 62 18 20
T3 46 21 33
T4 32 18 50
Over the past few years, two proposals—the so-called Brussels guidelines from Gre´goire et al., and the Rotterdam guidelines from Nowak et al.—emerged from the literature for the delineation of the neck node levels.
Recommendations:
1. The entire operative bed should be covered, especially in case of ECE, as tumor cells might have spilled during surgery.
2. In case of pathological involvement of level II, it is recommended to extend the upper border of level II to include the undissectedretrostyloid space upto the base of skull.
3. In case of pathological involvement of level IV & Vb, it is recommended to include the SCF in the CTV.
4. When pathological LN abuts or invades a muscle (paraspinal/subhyoid muscle) routinely not removed in RND/MND should be included in the CTV,at least for entire invaded level.
5. When pathological LN is located at the boundary with a level which has not been dissected, it is recommended to extend the CTV to include in the adjacent level.
The clinically & radiologically node negative neck should be treated
where the risk of nodal metastasis is thought to be >20 %
When tumor is found in lymph nodes from a neck dissection, adjuvant
radiotherapy is recommended unless there is only a solitary positive
node 3 cm in diameter without extracapsular spread.
If radiotherapy is delayed to more than 3 months after surgery because
of surgical complications, the potential risks of EBRT may outweigh
the benefits.
recommend growing GTV isotropically by 10 mm to produce a
CTV70.
The CTV70 is then copied to form the CTV44 which is expanded to
include other nodal levels at lower risk of occult nodal metastases.
Overall CTV-PTV margins should be 3–5 mm in each direction.
Hot-spots of 107 per cent within the mandible should be avoided.
When only one side of the neck is treated, an arrangement of
three coplanar beams can usually provide good tumour
coverage while sparing the contralateral mucosa and parotid
gland. At least one of the beams must have no exit dose through
the spinal cord for this organ to remain within tolerance.In
practice this means the angle of the posterior oblique beam is
chosen to provide best coverage of the PTV while avoiding the
cord (Fig. 10.4). A matched anterior neck beam is often
required to treat low neck nodes.
Where treatment is unilateral, anterior and posterior oblique
wedged fields arechosen, with a lateral field sometimes used to
improve homogeneity medially in the target volume. An
ipsilateral anterior neck field is matched to treat inferior neck
nodes if required.
Subsite-Specific Treatment and Results
Carcinoma of the Lip
Lymph node metastasis from carcinoma of the lower lip most
frequently involves the ipsilateral prevascular submandibular
nodes. Carcinoma arising near the midline of the lower lip
usually metastasizes to the submental lymph nodes.
Carcinoma at or near the commissure may rarely metastasize
to the facial nodes within the substance of the cheek.
Carcinoma of the upper lip may metastasize directly to the
upper cervical, preauricular, or submandibular nodes.
However, contralateral metastases are infrequent.
.
7
Lip
Early stage carcinoma of the lip can be managed with surgery or
radiation therapy. However, surgery is generally preferred for
small tumors (<2 cm). Although the local control of T1 and T2
squamous cancers of the lip is excellent with surgical resection,
disruption of the oral sphincter provided by the orbicularis muscle
can lead to oral incompetence if not properly reconstructed.
Therefore, a number of reconstructive methods have been
developed to help preserve oral sphincteric function even
following large excisions for T3 and T4 lesions. For these larger
lesions, surgery( W/E with marginal/segmental hemimandible
resection) followed by radiotherapy/ chemoradiotherapy remains
a standard therapy.
RadiotherapySurgery
Usually indicated for upper lip
moderately large (>3 cm) infiltrative
lesions that would otherwise require a
complicated plastic surgery with less
satisfactory cosmetic and functional
results.
Tumors involving the commissure
because surgical excision of the
commissure, would not yield
satisfactory cosmetic and functional
results.
Elderly patients who are at a high risk
for complications from general
anesthesia or who have persistent or
recurrent disease after surgery.
Postoperatively when the surgical
margin is inadequate, there is invasion
of the soft tissues of the neck caused by
cervical lymph node metastasis, and in
combination with surgery for advanced
resectable disease.
preferred for majority of lower lip small lesion up to 2 cm in diameter that do not involve the commissure,
young patients,
very advanced disease with bone invasion,
cervical lymph node metastases,
recurrent disease after radiotherapy.
Advanced lesions with bone, nerve, or node involvement frequently require a combined modality approach.
Surgical treatment for early lesions (0.5–1.5 cm) uses a V- or
W-shaped excision, depending on the size of the defect,
which facilitates cosmetic primary closure. If the vermilion is
diffusely involved with little or no involvement of the
muscle, a vermilionectomy may be performed and the
mucosa from the labial vestibule of the oral cavity advanced
to cover the defect.
Mohs and Snow, reported the results for 1,448 patients
treated with microscopically controlled surgery for SCCs of
the lower lip between 1936 and 1976. Eighty-three percent
had cancers less than 3 cm in diameter, with a 5-year cure
rate of 96.6%. For 192 patients with cancers that measured 2
cm or more, the cure rate dropped to 60%. For patients with
grade 1 or 2 SCC, the 5-year cure rate was 96%, as
contrasted with 67% for 81 patients with grade 3 or 4 SCC
Radiotherapy modalities commonly used for carcinoma of the lip include external-beam radiotherapy with orthovoltagex-rays or electrons & interstitial implants with radium or iridium.
The treatment volume should include the lesion with adequate margins. Leukoplakic changes on the lip adjacent to the lesion should also be included in the treatment volume.
For small superficial tumors, a single field with 100- to 150-kV x-rays is sufficient. For deeper, more advanced tumors, 200- to 250-kV x-rays or electrons are usually used.
The optimal dose-fractionation schedule depends on the volume of irradiation. For small lesions (<2 cm in diameter), a dose of 45 Gy to 50 Gy in 15 fractions over 3 weeks is usually adequate, with good cosmetic results. For larger lesions, more protracted treatments with 50 to 70 Gy in 4 to 7 weeks are often used.
When primary radiotherapy is used to treat lip cancer, the target volume should include the primary tumor plus a 1.5- to 2-cm margin for orthovoltage or a 2-2.5 cm margin for electron. For early stage lesions, photons in the orthovoltage range (100 to 250 keV) or electrons may be used. The electron energy should be chosen based on the thickness of the lesion (commonly 6 to 9 MeV).
Effort should be made to shield the underlying gum, dentition, and mandible as appropriate. This can be accomplished with the use of oral shields or cerrobendstents. The recommended dose is 50 Gy in 4.5 to 5 weeks for smaller lesions and 60 Gy in 5 to 6 weeks for larger lesions. Some institutions have used an approach where external beam radiation is given to approximately 40 to 50 Gy followed by a brachytherapy boost, or smaller lesions are treated by primary brachytherapy alone.
An important consideration in managing lip cancer is the risk of regional metastatic disease. Generally, the risk of regional lymph node metastatic disease for T1 and T2 cancers of the lip is lower than for stage-matched tumors of other oral cavity sites. Thus, elective neck dissection is recommended for patients with T3 and T4 carcinomas of the lip; however, it may not be warranted for all T1 and T2 lesions. T3/4 tumors are treated with opposed lateral fields with inferior border is at the thyroid notch and the posterior border is at the posterior aspect of the spinousprocess. When regional nodes are positive,a low neck field is matched to the inferior border of the opposed lateral fields.
Some institutions have used as moustache field for elective irradiation of the perifacial lymphatics (approximately 50 Gy) for more advanced upper lip lesions. Sentinel lymph node biopsy may prove to be useful in the management of patients of node-negative lip cancers, but further clinical investigation in this area is needed.
dobbs Most tumors are treated with electrons or superficial X-rays.
The PTV should be by the 90 per cent isodose of the electron or superficial X-ray beam. Once the PTV has been defined and marked as above, isodose charts are used to select the required energy to give 90 per cent coverage from the surface to the deep margin.
Tissue equivalent bolus is used as required either to increase the surface dose or to reduce unwanted deep penetration.
The applicator size can then be calculated. If electrons are used, the 90 per cent isodose in the lateral plane is 3–5 mm inside the edge of the applicator, which represents the 50 per cent dose. Electrons bow inwards at depth at higher energies, so if a high energy is chosen the applicator size will need to be correspondingly larger to avoid underdosing the deep lateral margin.
A 3–4 mm thick lead mask is then constructed with a cut-out area over the target volume. An intraoral lead shield is used to protect the gums and teeth from the exit beam. It is lined with wax to absorb secondary electrons.
.
8
IMRT is not indicated except for the occasional patient with
advanced neck disease and/or clinical PNI, when it is
necessary to extend the dose distribution to the skull base
and reduce the dose to the contralated parotid. For more
advanced lesions, combining chemotherapy with EBRT is
appropriately considered.
Definitive RT Brachytherapy
1. T1N0: 2/50 Gy f/b boost to 56-60 Gy.
Alternately 45Gy/3 Gyfraction.
2. T2N0: 2/50 Gy f/b boost to 60-66 Gy
3. T3N0: 2/50 Gy f/b boost to 60-70Gy & level I & II are treated.
4. T4 or LN+: 2/50 Gy f/b boost to 66-70Gy & level I & IV are treated.
1. BRT alone : for T1-2
lesion, LDR dose : 60-70
Gy at 0.8-1 Gy/hr.
2. As boost 2-4 wks after
EBRT(50-54 Gy) : LDR
dose15-30 Gy.
Indications:T1-2N0 Lesions
T.V.:
Dose: 50-70Gy in 5-7 days LDR
Technique:
Rigid afterloading needles maintained in place by Template
Classical plastic tubes
Spacers to decrease dose to gingiva, teeth & other lip
lip The clinical target volume includes all visible and palpable tumour
extensions with a safety margin of 5 - 10 mm according to the different directions. Because there is little movement of interstitial implanted sources when adequately fixed with templates or plastic tubes, the PTV usually corresponds very closely to the CTV.
Technique:
It is nowadays classically performed with Iridium192, applied in small source carriers. These are usually hypodermic needles but also guideneedles, classic nylon tubes, silk threads, small vascular catheters, guide gutters, or a combination of more of these afterloading techniques in the same patient. Whenever possible a custom made protection device should be prepared to shield the upper lip and the lower gum (fig 8.1). The protector consists of a 2mm lead shield placed between both lips and the mandible, contained in an acrylic mouthpiece.
Brachytherapy
Source carriers like: hypodermic needles , guide needles, classic nylon
tubes, silk threads, small vascular catheters, guide gutters, or a combination
of more of these afterloading techniques in the same patient are used.
Whenever possible a custom made protection device should be prepared to
shield the upper lip and the lower gum.
Target volume: All visible & palpable tumor with 5-10 mm margin.
8.1A: Acrylic custom made protection Fig 8.1B: X-Ray of implant with protector.
device containing a 2mm lead plate for shielding
upper lip and lower gum during brachytherapy
Typical hypodermic needle implant of the lip in an
equilateral triangular configuration with
protection device in place. Needles have been afterloaded
with Iridium 192 wires (2A). X-Ray control
(2B).
These are hollow, bevelled needles with small outer
diameter (0.8mm) and variable length (4 to 8cm),
open at both ends. The rigid fixed steel and template
system avoids collapse of the sources.
Used in lip tumors of less than 3cm in largest
diameter, not involving the lateral commissurae. The
inner diameter is 0.5 mm and can be afterloaded
with 0.3mm iridium192 wires.
Hypodermic needles
These are hollow, bevelled needles with small outer diameter (0.8mm) and variable length (4 to 8cm), open at both ends. They cause little trauma and can be directly inserted in the tissues. This technique is the optimal technique for lip carcinoma (Fig 8.2). The rigid fixed steel and template system avoids collapse of the sources due to the elasticity of the soft tissues.
Templates with predrilled holes (0.6 mm) in a triangular configuration and with spacing of 10 to 15mm should be available in the department.
Hypodermic needles can be used in lip tumours of less than 3cm in largest diameter, not involvingthe lateral commissurae. The inner diameter is 0.5 mm and can be afterloaded with 0.3mm iridium192 wires.
Classis nylon tubes They have a larger diameter than hypodermic needles. They are
more flexible, allowing a better adaptation to round surfaces.
However it is more difficult to keep good parallelism between
tubes over the whole length of the treated volume.
Large plastic tubes are therefore indicated for larger masses, or
when the lateral commissurae or cheek are involved.
Interstitial implant in three planes :
the deep and middle plane with plastic
tubes,
the superficial with hypodermic needles
They have a diameter which is larger (1.6 to 1.9mm) than hypodermic needles. They are more
flexible, allowing a better adaptation to round surfaces (Fig 8.3). However it is more difficult to keep
good parallelism between tubes over the whole length of the treated volume Large plastic tubes are
therefore indicated for larger masses, or when the lateral commissurae or cheek are involved.
Their loading has sometimes to be delayed as long as necessary for regression of the post
brachytherapy trauma and oedema.
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9
Silk threads
They are seldom used for the brachytherapy of lip cancer, unless it
is a very small lesion preferentially in the upper lip. They can be
used in the completion of a plastic-tube implant, or in
combination with hypodermic needles. For example when a part
of the tumor bulges out of the implanted area and a sub-optimal
dosage is achieved, this can be corrected by an additional silk
thread that can “warm up” the under-treated area.
Basal cell cancer of the uppr lip implanted with the silk thread technique (4A)
and cosmetic result two years later (4B).
Small vascular catheters
Their indications for lip cancer are similar to the indications
for silk thread and small plastic tubes.
Guide gutters
Guide gutters are only exceptionally used. They are reserved
to treat lesion with limited lateral
commissura involvement.
Treatment Outcome
Results of radiotherapy in select series of patients treated with radiotherapy for carcinoma of the lip are shown in Table 29-2. Control of the primary lesion can be achieved with external-beam irradiation or interstitial implants in the majority of patients. Those with recurrent disease after radiotherapy or cervical lymph node metastasis are usually treated surgically. The local control rate by interstitial implant is comparable to that achieved with external irradiation, although for larger lesions, better cosmetic results are obtained with protracted external-beam radiotherapy.
Complications of Treatment
Oral competence, which permits patients to control oral secretions and effectively suck, speak, and swallow, requires the sphincteric function of an intact orbicularis oris muscle. Hence, disruption of the sphincteric function resulting from division of the orbicularis oris should be restored. Microstomia and drooling secondary to oral incompetence may occur after a large flap reconstruction. If the oral opening is too small, the patient may not be able to inset a denture.
There will be some atrophy of the irradiated tissues; this progresses with time. Soft tissue necrosis may occur; this problem is reduced by schemes that prolong the treatment.
MSKCC
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10
Carcinoma of the Oral Tongue Routes of Spread Carcinoma of the oral tongue usually
spreads by direct invasion into the floor of the mouth, anterior tonsillar pillar, base of tongue, and mandible. Approximately 30% to 40% of the patients have cervical lymph node metastasis on presentation. The thickness as well as the T stage of the tongue lesion is directly correlated with the incidence of lymph nodal involvement.The subdigastric(level II) nodes are most frequently involved. The submandibular and midjugular lymph nodes are less commonly involved, and the submental, lower jugular, and posterior cervical nodes are rarely involved. The distribution of lymph nodes reported by Lindberg is shown in Fig. 29-12.
Oral Tongue
Selection of Treatment Modality
Both surgery and RT result in cure rates that are similar for similar stages. The disadvantages of surgery include removal of part of the tongue and the decision of whether or not to do a neck dissection for the N0 neck. The disadvantage of RT is the risk of necrosis.
Excisional Biopsy (TX)
Excisional biopsy of a small lesion may show inadequate or equivocal margins. An interstitial implant or re-excision will produce a high rate of local control.
Early Lesions (T1 or T2)
A partial glossectomy with primary closure or a skin graft may be done transorally and is usually the preferred therapy. Depending on the depth of invasion, an elective neck dissection may be indicated. Postoperative radiation therapy is recommended for patients with large primary tumors (T3, T4), close or positive surgical margins, evidence of perineural spread, multiple positive nodes, or extracapsular extension, invasive pattern. In regard to an invasive pattern, multiple studies have demonstrated that the risk of cervical lymph node metastases is much greater for tumors with a depth of invasion of 5 mm or greater.
In patients with positive margins or extranodal extension, a postoperative chemoradiation approach has been shown to be superior to radiation alone in the analysis of pooled RTOG and EORTC data by Bernier and colleagues, and now is the standard of care, albeit with increased toxicity.
Primary radiotherapy techniques can be used for patients who refuse or are unable to tolerate surgery.
Moderately Advanced Lesions (T2 or T3)
The preferred treatment for the majority of these patients is partial glossectomy, neck dissection, and postoperative RT/ CRT based treatment as previously described.
Advanced Lesions (T4)
Total glossectomy and sometimes a laryngectomy combined with postoperative RT or chemoRT. Some patients are best treated with palliative intent.
Surgery Combined
Surgery is indicated for small lesions (<1 cm) located on the dorsum, the tip, or the lateral border of the tongue that can be excised without resulting in dysfunction, especially in young patients.
Surgery is also preferred in elderly patients who tolerate partial glossectomy better than radiotherapy and in whom preservation of speech is not important.
Certain carcinomas of the tongue arising from syphilitic glossitis, lesions that are edematous and deeply infiltrative, lesions that have invaded the mandible, lesions that have invaded the glossopalatine sulcus, and advanced lesions with multiple lymph node metastases are best managed with combined surgery and radiation with or without chemotherapy.
Surgical approaches to oral tongue cancers : transoral, transcervical,
or alternatively via mandibulectomy to obtain the exposure necessary
to achieve adequate margins.
Partial glossectomy is the most common procedure performed for
oral tongue cancers, and the extent of resection depends on the size
and growth pattern of the tumor.
The tongue is essentially comprised of skeletal muscle; wide margins
are encouraged to avoid retraction of muscle fibers with microscopic
tumor cells that serve as a source of local recurrence.
Total glossectomy may be indicated for extensive tumors or those that
involve the intrinsic tongue musculature. It can result in difficulty
with deglutition, maintenance of an adequate airway & aspiration .
Thus laryngectomy may be necessary in some cases. However,
properly selected patients with adequate postoperative rehabilitation
(laryngeal suspension and palatal augmentation) can be treated with
total glossectomy without laryngectomy.
Tumor size and depth of invasion are currently the most reliable indicators for predicting cervical metastases in patients with oral tongue squamous-cell carcinoma.
Because of the high risk of nodal metastases the neck should be addressed either with surgery or radiation in all but the earliest tumors of the oral tongue.
Patients with small oral tongue cancers should be considered for neck therapy, particularly if the primary tumor exhibits extension onto the floor of mouth or there is increased tumor thickness. Treatment of the clinically negative neck is most often accomplished by supraomohyoid neck dissection. Elective neck dissection appears to result in better overall cancer outcome than observation.
Potential pitfalls of observation include a salvage rate of only one-third for patients who do not undergo elective neck dissection along with resection of the oral cavity primary.
For patients with a clinically and radiographically N0 neck, with well-lateralized disease, or those who do not undergo neck dissection, 50 to 54 Gy should be considered to the ipsilateral neck as elective nodal irradiation (Fig. 41.16).
Patients with advanced lesions and high-risk disease (particularly with multiple positive nodes) should receive radiation treatment to the bilateral neck.
.
11
Recurrence in the primary lesion after radiotherapy is
difficult to salvage by surgery, with one study quoting 5-year
actuarial survival rates of 39%, and 27% for locoregional
recurrence. Local recurrence after treatment with
glossectomy alone has a similarly dismal prognosis, with
some studies reporting less than 10% of patients being
successfully salvaged at 4 years after being diagnosed with
recurrent disease. Metastatic cervical lymph node metastases
that develop after the primary lesion has been controlled can
be successfully salvaged, although survival after neck
recurrence has been documented to be as low as 18 months.
Opposing lateral fields are used to encompass the tongue and upper neck bilaterally, and this volume should be treated to 50 to 54 Gy(see Fig. 41.12A and Table 41.1).
In patients with unilateral lymph node metastasis, the rate of contralateral occult node metastases has been found to be high in OCC, up to 35% to 40%.Therefore, contralateral nodal treatment in all patients with carcinoma of the oral tongue is advocated because of its aggressive behavior and because it is not a well-lateralized structure such as the buccal mucosa.
With opposed laterals, the superior border is 1-1.5 cm above the dorsum of the tongue or 2 cm above tumor, inferior border is at the thyroid notch, posterior border is placed at the posterior aspect of the spinous process, the anterior border is 2 cm anterior to the tumor. When LN+, a low neck field is matched to the inferior border of the opposed lateral fields.
3DCRT & IMRT are preferred approaches
Superficial T1 lesions can be treated with brachytherapy alone. Commonly, 192Ir temporary implants are used to deliver 50 to 60 Gywith dose rates of 40 to 60 cGy per hour. Although the primary lesion may shrink after the external irradiation, the treatment volume for the interstitial implant is usually determined before any treatment is initiated.
For infiltrating T1 or T2 lesions, a combined approach using external beam and a brachytherapy or intraoral cone boost should be considered. As a boost before or after EBRT ( 45 Gy), interstitial brachytherapy 25-30 Gy or intraoral cone 15-24 G Gy may be used.
Definitive RT for advanced lesions, without chemotherapy:> 72 Gy ( 1.8-2 Gy/ fx), (altered fractionation is recommended)
Definitive chemoradiation: 70 Gy/2Gy per fx.
Postop EBRT:50-54 Gy/ 1.8-2 Gy per fraction followed by boost to 60-66 Gy to high risk areas including primary surgical bed, close margins, extranodal extension, nodal involvement, LVSI or PNI. Postoperative treatment should include the site of primary tumor, dissected neck, and draining lymphatics. The lymph node areas are treated from 54 Gy, for uninvolved lymph nodes being treated electively, to 60 Gy.
Oral tongue & Floor of mouth Brachytherapy Interstitial implant is an integral part of radiotherapy for carcinoma of
the oral tongue if definitive radiotherapy is the primary treatment approach.
The implant dose is directly correlated with local control. External radiotherapy alone is not recommended, as it is rarely successful.
Early superficial lesions can be controlled with a single-plane interstitial implant or peroral radiotherapy alone. For lesions greater than 1 cm in thickness, double-plane or volume implants in combination with external irradiation are usually used.
Brachytherapy has also been used in the postoperative setting for T1-2-N0
squamous cell carcinomas of the oral tongue and the floor of mouth with close or positive margins. The recommended dose is 60 Gy. High rates of locoregional control, close to 90%, with low risk of chronic sequelae have been reported.
The most important step in treatment planning for interstitial implants is the determination of the treatment volume. Sometimes the true extent of the tumor cannot be adequately determined without anesthesia because of pain. With the patient under general anesthesia, it is not uncommon to find a tumor more extensive than anticipated.
For interstitial implants of carcinoma of the tongue and floor of the mouth, dose rates in the range of 30 to 100 cGy per hour for the minimum tumor dose have been commonly used when low-dose rate (LDR) brachytherapy is the treatment approach. Although some authors recommend adjustments of the total dose according to the dose rate; Mazeron and coworkers suggest that for dose rates between 30 and 100 cGy per hour, no adjustment of total dose is indicated. Overcorrection of dose for reduced overall treatment time may lead to a high incidence of local recurrence.
Localization films of the implant are usually taken on the day of the procedure.
Computer dosimetry provides detailed information on the dose distribution within the implant volume. The dose distribution in several parallel planes intersecting the tumor volume should be obtained. An isodose curve that encompasses the entire tumor volume on all the planes that intersect the volume should be used to calculate the minimum tumor dose.
Sometimes part of the implant may be removed during the course of treatment when there is a volume of overdosage within the implant.
The optimal minimum tumor doses for local control vary with the size of the primary lesions. For T1 and select small T2 lesions, the implant alone is used with a dose of 60 to 70 Gy. For larger T2 lesions, a total dose between 75 to 80 Gy is delivered by using both intestitialimplant and external-beam radiotherapy, with 30 to 40 Gy being a typical dose delivered by external-beam radiation.
The incidence of soft-tissue and bone necrosis depends on the total dose as well as on tumor volume, but is independent of the dose rate. It is important to separate the ribbons from the mandible by the use of dental rolls sutured in place.
HDR fractionated interstitial brachytherapy is the preferred
treatment nowadays. A phase III trial of high- and low-dose
interstitial radiotherapy for early oral tongue cancer showed that
HDR can be an alternative to LDR, with similar rates of local
control and the advantage of eliminating exposure to the medical
staff.
If not using HDR, an afterloading technique using iridium seeds
is preferable because of the reduced radiation exposure to the
medical and paramedical personnel. The afterloading technique
also allows more time for optimal placement of needles, because
no radiation exposure occurs during the procedure. The dosing
regimen for HDR brachytherapy is typically 54 to 60 Gy in 9 to
10 fractions.
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12
Oral Tongue:
Indications: T1 N0, T2 N0 < 3cm lesion
T.V.: GTV + 5 mm margin
Dose: Alone:60-65 Gy LDR
Boost 20-25 Gy after EBRT dose of 45-50 Gy
Techniques: Guide-gutter technique
Tongue The aim should be to treat the gross tumour volume which is
usually palpable plus a margin of at least 5mm all around it. It should be remembered that the lower end of hairpin and loop implants have no crossing sources as they do at the top and the length of the limbs need therefore to be long enough to ensure the volume is adequately covered.
7 Technique
7.1 Pre-planning:
Before going ahead with the implant it is necessary to measure the tumor carefully and plan the exact number of radiation sources to be used with their length and separation. This will allow a provisional dosimetry to be performed so that a source activity can be chosen to deliver a dose rate of 40 to 50cGy/h during the implant.
1.Guide-gutter technique: Iridium wire hairpins are prepared with a fixed separation of
12 mms. This limits the width of volume which can be treated to approximately 15 mm and the technique can therefore only be used for smaller tumors (no more than 30 mm in length).
The implant can be performed with the patient sitting upright under LA and sedation or rarely under GA.
The number and length of hairpins to be used is prehandedlydecided from the provisional dosimetry. The aim is for the sources to be equidistant, parallel and straight and to cover the target volume. The first phase of the implant is performed with inactive guide gutters (inactive device). These are introduced into the tongue with the help of fluoroscopy which ensures that they are parallel and equidistant.
For tumors that are near the tip of the tongue the anterior
needle will be reflected backwards by the mandible. This
should be accounted for before beginning the implant so that
there is no divergence orconvergence of the needles at depth.
(Fig 9.1) The guide gutter is first inserted angled towards the
mid line of the tongue but once within the muscle it is
straightened out so that the lateral limb of the hairpin runs 3
to 4 mms below the mucosa of the lateral border of tongue
(Fig 9.2).
The separation between the hairpin guides should be 10 to 15
mm.
Once fluoroscopy has confirmed that the hairpin guides are
parallel and equidistant, a black silk suture is run under the
bridge of each one (Fig 9.3).
Local Anesthesia
Fig 9.2 : Implantation of the guide gutter, starting with the
posterior, followed by the anterior with the third
implanted in between
When the guide gutters are in position, the radioactive hairpins
can be cut to the desired length; it is usual to use 4 to 5 cm for
implantation of the lateral border of tongue. The active hairpin is
introduced into the guide gutter starting with the most posterior
and slotted down the stainless steel guide. Once in position the
hairpin is held in position in the tongue with a Reverdin needle
and the inactive stainless steel guide withdrawn from the tongue.
The preprepared suture is then tied over the bridge of the hairpin
to secure it within the tongue.
Implantation of the guide gutter, starting with
the posterior, followed by the anterior with the
third implanted in between
Insertion of the silk suture. And Loading of the iridium hairpin inside the gutter.
Replacement of the guide gutter by the iridium hairpin. and End of the implantation : the three
hairpins are implanted and sutured.
After the implant is completed, AP and lateral radiographs
are taken, which will be used for computerized dosimetry
AP X-ray Lateral X-ray
Computerized dosimetry : sagittal planeComputerized dosimetry :
reference volume (PTV).
The “classical” guide-gutter technique as modified by
J.P. Gerard and his team [15] is shown in figures
Bleeding can sometimes occur on insertion or
removal of a guide gutter; this nearly always stops
after 3
to 4 minutes of pressure.
Fork
Applicator in situ
X-ray : lateral view
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13
2. Plastic loop technique
Implantation of the two posterior steel needles After Nylon cordlet introduction inside the Needles, the needles
are removed and replaced by the plastic tube, pulled with the
cordlet.
Plastic loop Technique: The loop technique allows a wider separation between the sources than the
fixed 12 mm separation of a hairpin. It therefore can be used to treat larger volumes. It also has the advantage that iridium wire can be inserted into the plastic tubes with a remote afterloading machine that reduces the risk of exposure; in case of local oedema inducing the risk of displacement of the plastic tubes, it offers the advantage that one can wait for an acceptable local status before loading the iridium wire.As for the guide-gutter technique, the number of loops, their separation and length should have been planned before performing the implant following the rules of the Paris system. Loop techniques are performed under general anaesthesia. It is helpful before starting to outline on the skin of the under surface of the jaw the projection of the tumor to be implanted and the position of the mandible.
The implant is performed by creating a loop of plastic tubing which goes from the skin up over the tongue and down through the skin again. The loop is formed by passing a hollow stainless steel needle through the skin into the tongue (Fig. 9.18). A parallel stainless steel needle forms the other limb of the loop. A nylon cord is passed up the stainless steel needle where it exits into the oral cavity and is then passed down the other needle to form a loop. The stainless steel needles are then removed. A length of plastic tubing with a 1.6 mm outer diameter is threaded over the nylon cord and clamped over the cord at its end. The plastic tube is then pulled into the mouth by the nylon cord so that it reforms a loop passing from the skin over the tongue and back out of the skin (Fig 9.19).
Three or four loops are inserted into the tongue depending on the volume to be treated with a separation between each loop which should ideally be between 15 to 18 mm. To respect the rules of the Paris system and to assure a better homogeneity of dose distribution, the distance between the “legs” of eachloop is the same as the distance between the different loops.
An inert marker wire is passed up the loop so that the position can be identified on radiographs for dosimetry. The plastic rubes are rinsed with a heparin solution (Fig 9.21). A nylon ball and lead washer are passed over the ends of the plastic tube in preparation for fixing the implant once it is loaded.
Two shielding devices are systematically used in oral-cavity cancers: the first one is a radiotransparent device for radiograph control (Fig 9.22), the second one, identical to the previous one, is made of lead (Fig 9.23) in order to decrease the dose to the critical organs.
Plastic tubes are cleaned with a tubes with metallic
heparin solution. B)Fixation of the. buttons.
A, B : Shielding system, tailored for each patient (must be
evaluated according to the GTV, to
the brachytherapy procedure, and to the patient tolerance).
After check radiographs have confirmed that the
loops are equidistant and parallel the implant can be
Two shielding devices are systematically used in oral-cavity cancers:
the first one is a radiotransparent device for radiograph control (Fig
9.22), the second one, identical to the previous one, is made of lead
(Fig 9.23) in order to decrease the dose to the critical organs. After check radiographs have confirmed that the loops are
equidistant and parallel the implant can be loaded by passing
a pre-encapsulated iridium wire up the pre-implanted plastic
tube to form a loop of iridium wire over the tongue (Fig
9.24, 25). The radioactive wire is maintained in place by
clamping the inert ends of the plastic inner tubing to the
hollow plastic tube loop to fix their position.
Remote Afterloading:
It is difficult for a remote afterloading device to negotiate the radioactive source around the tight curve of a plastic tube loop. The implant therefore has to be done with straight line (27) sources. Care needs to be taken to avoid a cold spot at the top of the implant at the surface of the tongue where retraction of the isodoses can result in a cold spot at the tongue surface which may be involved by tumour. This is achieved by allowing the plastic tube to protrude 4 to 5 mms above the tongue surface where it is maintained in place with one or two plastic buttons. (27) The afterloading machine also must be programmed to double the dwell time at the top three source positions in order to achieve a source distribution similar to the old Manchester Indian Club needle with increased activity at the uncrossed top end. Brachytherapy may also be indicated as postoperative treatment; in this case only the plastic-tube
technique should be used.
During the implant Although patients are usually able to speak and swallow with the
implant in place, it is good practice to maintain adequate hydration
with intravenous fluids & start on ryles tube feeding.
Antibiotics cover during the implants and for 1 week after the
implant.
Patients are also encouraged to irrigate the mouth with salt and
baking soda solutions or half-strength peroxide solutions during
and after the implant period.
Analgesics are prescribed whenever necessary. The peak reaction
of mucous membranes usually does not occur until several days to
1 week after the implant.
Complication
Because interstitial radiotherapy is an integral part of radiotherapy in patients receiving radiotherapy alone for carcinoma of the oral tongue, a small area of the mandible usually receives a dose in excess of 75 Gy. The incidence of osteonecrosiswas 19% in the series reported by Delclos and coworkers. Most of the necrosis healed with conservative management, although only 35% of the bone necrosis in that series required surgical treatment, for a total of 6% of patients requiring surgical management. Another series reported a 38% complication rate, such as erosive ulcerations and bone exposure, in patients who received brachytherapy for stage I and II disease.
The patients who also received external-beam radiotherapy in addition to brachytherapy had higher rates of complications than those treated with brachytherapy alone, but the incidence of neck metastases occurred in 31% to 51% of patients in whom the neck was not electively irradiated.
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14
Treatment outcome There have been multiple studies on the outcomes of patients
treated with surgery in carcinoma of the oral tongue. One recent retrospective study from Japan demonstrated a superiority of surgery over brachytherapy in stage I and II tumors, with 5-year overall survival rates for the LDR, HDR, and surgery groups of 84.0%, 72.9%, and 95.4%, respectively.
Another study by Aksu and colleagues compared definitive radiation with surgery and postoperative radiation in 80 patients with stages I through IVA disease.The patients that received surgery and postoperative radiation therapy had a 5-year overall survival advantage versus those treated with definitive radiation alone (49% versus 16%, respectively). Studies such as these confirm that when feasible, surgery should be performed as the definitive treatment modality in patients with oral tongue cancer.
Definitive radiotherapy results for carcinoma of the oral
tongue are given in Table 29-4. Most of the patients in the
series reported by Wendt and associates[75] and Mazeron and
associates did not have cervical lymph node metastasis at the
time of treatment, whereas 50% of the patients in the series
reported by Fletcher presented with cervical lymph node
metastasis. As noted previously, the incidence of occult
metastasis in early-stage squamous cell carcinoma of the oral
tongue is between 20% and 48%.
Survival Long-term survival in carcinoma of the oral tongue is directly
related to the stage of disease. In a series of 204 patients treated between 1940 and 1971, reported by Fu and associates, the overall 5-year actuarial survival was 32% and determinate survival was 47% for all stages. The prognosis for patients who had cervical lymph node metastasis on presentation and persistent or recurrent disease at 3 months after treatment was significantly poorer than the prognosis for patients who had no cervical lymph node metastasis on presentation and those who were free of disease at 3 months after treatment.
A recent series of 370 stage T1 and T2 cases reported by Shibuya and associates showed that the 5-year primary tumor control was 85% for superficial lesions, 70% for exophytic lesions, and 45% for infiltrative lesions. The 5-year overall survivals for stages T1, T2a, and T2b were 84%, 78%, and 72%, respectively.[80]
Carcinoma of the Floor of the Mouth
Carcinomas of the floor of the mouth usually spread by direct
invasion into the tongue, the lower alveolar ridge, the mandible,
and the submandibular glands.
Approximately 30% of the patients have cervical lymph node
metastasis on presentation. The submandibular lymph nodes are
most frequently involved. Metastasis to subdigastric nodes,
midjugular nodes, and submental nodes are less frequent.
The incidence of lymph node metastasis is directly proportional to
the stage of the primary lesion; 9% for T1 lesions, 25% for T2
lesions, and 68% for T3 and T4 lesions (Fig. 29-15).
Similarly, 20% of the patients without initial lymph node
metastasis subsequently develop cervical lymph node metastasis.
Early stage floor of the mouth cancer can be treated effectively by radiation therapy or surgery. However, surgery is usually preferred in patients who are medically operable because proximity of the tumor to the mandible confers a significant risk of radiation-induced ulceration and osteoradionecrosis. Small lesions of the floor of the mouth are most commonly resected transorally. The surgical defect can be left to heal by granulation or reconstructed with a split thickness skin graft or local flap.
Advanced stage floor of the mouth cancers are usually managed by a combination of surgery and radiation or chemoradiation, especially when there is invasion of the mandible and the presence of large or multiple cervical lymph node metastases or extensive involvement of the musculature of the tongue.
For medically inoperable patients, or unresectable stage T4b disease, a combination of chemotherapy and radiotherapy should be considered.
Surgery is used in the treatment of recurrent disease after radiotherapy.
Small (T1 and T2) lesions may be treated with a combination of
external beam radiation and boost with interstitial implant or
intraoral cone. Superficial or exophytic T1 cancers are treated
with either brachytherapy or intraoral cone RT to
approximately 65 Gy and the neck is observed. Lesions that are
suitable for intraoral cone RT may be boosted with this
technique prior to EBRT of the primary lesion and upper neck.
Use of EBRT alone results in suboptimal cure rates and is
discouraged
For lesions that are very close to the mandible, brachytherapy is
contraindicated .Infiltrative lesions that are tethered to the
mandible and advanced lesions following surgical resection
should receive postoperative radiation.
In the surgical management of floor of the mouth cancer, special attention should be paid to mandibular invasion. A cancer that appears to involve only the periosteum or that only superficially invades the mandible can be removed via a transoral or transcervical approach in which a marginal mandibulectomy is performed.
Segmental mandibulectomy may be necessary for patients with a limited mandibular height when there is no direct bone invasion, because marginal mandibulectomy may leave these patients with insufficient bone, placing them at high risk for radionecrosis or pathologic fracture. A full thickness segmental resection may be necessary if there is frank bone invasion.
For advanced cancers, resection of the anterior arch of the mandible may be necessary. Defects of the anterior segment of the mandible require reconstruction with bone, usually with a free fibular or iliac crest graft.
Management of the neck is similar to that for other tumors of the oral cavity. Patients with lesions <2-mm thick with no adverse pathologic factors and a clinically and radiographicallynegative neck may be observed after primary resection. Otherwise most N0 patients should receive either selective neck dissection or radiation therapy. Patients with advanced lesions and high-risk disease (particularly with multiple positive nodes) should receive radiation treatment to bilateral necks.
Combined Treatment Policies
Postoperative RT is preferred, because the risk of bone complications and fistulae is higher with preoperative RT. Concurrent chemotherapy may be necessary based on pathologic findings. Preoperative RT may be used if the patient has a large fixed node.
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15
With opposed laterals, the superior border is 1-1.5 cm above
the dorsum of the tongue ( 2 cm above the tumor).
A cork should be used b/w the teeth to exclude palate & if
possible , tip of tongue , from field.
Level I nodes are always treated & level II is included for depth
of invasion>1.5 mm ( with posterior border at the posterior
aspect of the spinous process).
The inferior border is at the thyroid notch.
The lower lip is excluded when possible.
When LN+ , a low neck field is matched to the inferior border
of the opposed lateral field.
Opposing lateral fields encompass the oral cavity tumor bed
and upper neck bilaterally, and this volume is commonly
treated to 50 to 54 Gy. High-risk areas (primary surgical bed,
positive/close margins, extracapsular extension, perineural
spread) may receive additional boost treatment up to 60 to
66 Gy.
The entire width of the mandibular arch is included and the
superior border is shaped to spare part of the parotid gland.
If the neck is clinically positive, the portals are enlarged to
include all of the upper neck nodes, and en face low neck
field is added. N0 Floor of the mouth
(Tongue extension −)N0 Floor of the mouth
(Tongue extension +)
If definitive radiation therapy is used with non-IMRT techniques, for most carcinomas of the floor of mouth without bone invasion, we recommend external-beam irradiation with 50 to 54 Gy delivered at 2 Gy per fraction, five fractions per week, to the primary lesion with adequate margins and the upper neck, including the submandibularand subdigastric nodes, followed by a boost to the primary lesion with 10 to 20 Gy using interstitial implant, peroralcone irradiation, or external-beam irradiation. The boost portion of treatment encompasses any visible tumor plus a margin, and we prefer using 3-D conformal radiotherapy (Fig. 29-16).
If IMRT is used as definitive treatment alone, the entire region can be treated using a dose-painting technique, delivering 70 Gy to the primary tumor and involved lymph nodes, 59.4 to 63 Gy in 1.8-Gy fractions or 60 Gy in 2-Gy fractions to the uninvolved but high-risk regions, and 54 Gy in 1.8-Gy fractions to the low-risk region. The lower neck is routinely irradiated when cervical lymph node metastases are present.
Similar to carcinoma of the oral tongue, the floor of the mouth is not a well-lateralized structure and thus the bilateral neck is generally treated in all cases. If a LAN field is used, the standard dose is 50 Gy in 2-Gy fractions or 50.4 Gy in 1.8-Gy fractions.
For advanced, unresectable lesions not amenable to implantation, patients can be treated with external-beam radiotherapy using accelerated hyperfractionation with a concomitant boost technique.
Brachytherapy Similar interstitial radiotherapy techniques for carcinoma of the oral
tongue are used for carcinoma for the floor of the mouth, as shown in Fig. 29-10.
Interstitial Irradiation
Implantation of T1–T2 lesions confined to the floor of the mouth with minimal extension to the mucosa of the tongue can be accomplished with iridium using the plastic tube technique.
The iridium seeds in nylon ribbons are afterloaded into nylon tubes extending from the skin of the submental region to the floor of the mouth. The nylon tubes are pulled in behind stainless steel needles, which are then removed.
For large lesions, the catheters are usually placed with the use of needles inserted through the submental skin to the dorsum of the tongue, to deliver an adequate dose throughout the tumor volume. If the tubes terminate in the floor of the mouth, the iridium ribbons must protrude at least 1 cm or have double-strength seeds at the tip. Alternately, longer dwell times can be used with HDR. The recommended LDR dose is 60-70 Gy & intraoral cone dose is 3Gy/fx to 45 Gy over 3 wks.
FOM brachytherapy In defining the CTV, a safety margin is chosen, which is at least 5
mm in all directions, except towards the mandible, which formsPlesiobrachytherapy:
Moulds can be used only for very superficial lesions (up to 5-mm target depth). The applicator must be adapted to the topography of the tumor. This is achieved by an appropriate choice of moulds, either standard or customised. Fixation and immobilisation are crucial.
7.2 Interstitial Brachytherapy:
Both guide-gutter and plastic-tube techniques are applicable (8,17,23). Specific guidelines for floor of-mouth cancer include the following: in order to decrease the dose to the mandible and consequently the risk of osteoradionecrosis, the contact of radioactive lines with the mandible should be minimised. Moreover, the radioactive lines must be inclined or bent according to the internal surface of the mandible, reducing even more the dose to the bone. a natural barrier.
Guide gutters as well as plastic tubes are therefore implanted
parallel to each other (Fig 10.1-7). To determine the distance
between the lines and the length of the radioactive lines,
three parameters must be considered: the target volume , the
situation of the tumor in relation to the mandible, and the
rules of the Paris system. Too large intersource spacing
should be avoided, to limit the dose delivered to the
mandible. With the guide-gutter technique, the distance
between the two parallel lines is fixed by the dimensions of
guide gutters: 12 mm. Ideal separation between the double
pins is consequently 12 mm. When it is not achievable, this
spacing should be kept, as far as possible, between 8 and 14
mm. (25) With the plastic tube technique, there is of course
more flexibility, but again intersource spacing should not
exceed 14 mm.
7.2.1 Guide-gutter technique
Local anaesthesia
Fig 10.2: Implantation of the guide gutter and
insertion of the silk suture
Fig 10.3:
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16
Loading of the iridium hairpin Removal of the guide gutter replaced
by the iridium hairpin
X-ray control: AP and lateral view
Shielding System
Plastic-tube technique
Tumors of the pelvilingual sulcus are implanted with two or three loops perpendicular to the mandible, according to a technique similar to that described for mobile tongue cancers (Fig 10.9,10). The external branches of the loops are as far as possible angled away from the inner table of the mandible so that just the apex of the loop is close to the bone, reducing the dose to this critical organ. If the tumor does not involve the ventral surface of the tongue, it is not necessary to load the bridge of the loop with radioactive wires, and two parallel wires then replace the loop.
Tumors superficially extending to the gingival mucosa, when not suitable for surgery because of age or poor health status, are implanted using the plastic tube technique (see figure) or with the crossing technique used for post operative implants. (13,23)
Postoperative implants, with or without external beam radiation therapy, may be indicated when surgical margins are positive or close to tumor. Large tumors of the floor of mouth that do not reach the gingiva but infiltrate the sulcus and the ventral surface of the tongue are often treated by wide resection using a myocutaneous flap. In this case, the implantation is not performed in the flap, but in the residual disease. (13,23)
The length of the radioactive lines is crucial. There is a clear relationship between this length and the risk of osteoradionecrosis and, while the target volume should be adequately covered (including the 5 mm safety margin), it is advised to avoid too long radioactive lines, particularly in contact with the internal surface of the mandible. With the guide-gutter technique, 2 to 3 cm long hairpins are often chosen. (8,11,17)
Tumors situated on or close to the midline are often implanted with five radioactive sources, two anterior, and three posterior (see figure), forming a trapezium, which can easily be divided into three equilateral triangles, thus respecting the rules of the Paris system. (8)
Anterolateral or posterior tumors are in most cases implanted with two or three guide gutters or two or three plastic loops, in a plane perpendicular to the mandible.
The plastic tubes are then implanted along the insertion of the flap; the anterior branch can also be implanted at a few millimetres from the suture, with the posterior branch in the flap. Tumors adhering to the gingiva are more difficult to treat, especially when the surgeon has resected the superior part (rim) of the mandible arch, leaving the inferior rim.
In this case, the mucosa of the tongue is used for covering the rim, and is sutured to the lip and/or the cheek. This mucosa is furthermore at high risk of local recurrence, and the plastic loops have to bridge the rim. To achieve this, the spacing of the external branches of the loops has to be greater than that of the internal branches, with regard to the mandible, and optimisation is consequently highly recommended. (23) A shielding system is always employed in order to decrease the dose to the teeth and the mandible and also to maintain the sources in good position throughout irradiation (Fig 10.8). This shielding system must be tested during the implantation procedure and may need modification according to the geometry of the implant and the tolerance of the patient. (9,16,17,20)
Plastic tubes are implanted by three
sagittal loops; the distance between the different
tubes is checked
Fig 10.10: X-ray control: AP view
Intraoral Cone Irradiation
Intraoral orthovoltage or electron cone RT requires daily
positioning by the physician and is preferable to interstitial
RT because there is little or no irradiation of the
mandible. An intraoral cone can be used for well-
circumscribed anterior superficial lesions and is easiest to
perform in the edentulous patient.
Management of Recurrence
Local recurrence after RT or surgery is heralded by
ulceration, pain, or increased induration. Recurrences have a
slightly elevated or rolled border, whereas necroses do not.
Biopsy should be done as soon as ulceration appears, if it is
within the original tumor site. Ulcers that appear on adjacent
normal tissues are likely due to RT and not cancer.
RT failure is managed by surgery. Surgical failure occasionally
is salvaged by re-resection and postoperative RT-based
treatment. Recurrence in the soft tissues of the neck is rarely
eradicated by any procedure.
Nodes appearing in a previously untreated neck are managed
by neck dissection with or without postoperative RT;
chemoRT is indicated if ECE is present.
Treatment Outcome
The results of definitive radiotherapy of carcinoma of the
floor of the mouth, as reported in several recent series, are
given in Table 29-5. Most patients were treated with a
combination of external irradiation and interstitial implants.
The control of the primary lesion is directly proportionate to
the stage of the disease. Control of the cervical lymph node
metastasis is also related to the N staging. Approximately two
thirds of cases of N1 disease (lesion < 3 cm in diameter) can
be controlled with radiation alone or in combination with
surgery.
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17
Results of Treatment
The local control rates for 170 patients treated with RT alone versus surgery alone or with RT between 1964 and 1990 at the University of Florida were T1, 79% versus 76% (P = .76); T2, 72% versus 76% (P = .86); T3, 45% versus 82% (P = .03); and T4, 0% versus 67% (P = .08).Local control rates for T1 or T2 cancers are comparable after RT versus surgery; patients with T3 or T4 lesions have improved local control if surgery is part of the treatment. The differences in 5-year survival between the two treatment groups were not statistically significant.
The results of brachytherapy alone or combined with EBRT for 448 patients treated at the Centre Alexis Vautin were reported by Pernot et al. and revealed the following 5-year local control and survival rates: T1, 93% and 69%; T2, 65% and 41%; and T3, 49% and 25%, respectively. Shorter time intervals between brachytherapy and EBRT were associated with significantly improved local control and survival for those who received both modalities.
Following treatment, the most common site of failure is the site of
the primary lesion, with or without simultaneous failure in the
cervical lymph nodes. Approximately 80% of the recurrences
appear within 2 years following treatment. Failure in the cervical
lymph nodes alone or in distant metastasis alone is rare.
A relatively large series of 160 patients from France showed that
brachytherapy alone offers excellent local control of 89% for T1
and T2 lesions with a 5-year survival of 76%. In spite of the good
local control rate of carcinoma of the floor of the mouth, actuarial
survival of these patients is poor, owing to a significant number of
deaths from intercurrent disease or a second primary cancer.
Follow-Up
There are two major difficulties in follow-up after RT: soft tissue ulcers and enlarged submandibular glands. An ulcer in the floor of the mouth within 2 years of treatment can be either recurrence or necrosis. If the lesion appears to be soft tissue necrosis, a trial of conservative therapy is adequate. Failure to stabilize or resolve is an indication for biopsy. A negative biopsy does not rule out recurrence, and repeat deep biopsies may be necessary. An enlarged submandibular gland(s) may be a sequel to obstruction of the submandibular duct; contrast-enhanced CT is useful to distinguish between an enlarged submandibular gland and tumor in a lymph node.
Follow-up of surgical cases may be difficult if skin grafts or flaps have been used because of the associated induration and thickness of the flaps. If the submandibular ducts have been reimplanted, stenosis may occur with subsequent enlargement of the submandibular glands.
Complications
Radiation Therapy
FOM has lower RT tolerance d/t increased risk of soft tissue injury & ORN. A small soft-tissue necrosis (approximately 10% to 21% of the patients, usually within 2 years of treatment) may develop, usually in the site of the original lesion where the dose is highest. These are moderately painful and respond to local anesthetics, antibiotics, & analgesics. Treatment with pentoxifylline 400 mg three times daily may be beneficial.
If the ulceration develops on the adjacent gingiva, the underlying mandible is exposed. These areas are mildly painful. They are managed by discontinuing dentures, local anesthetics, antibiotics, and smoothing of the bone by filing if needed. These small bone exposures do not often progress to osteoradionecrosis (ORN) and either sequestrate a small piece of bone or are simply recovered by mucous membrane. Severe ORN may require daily hyperbaric oxygen treatments for 4 to 6 weeks, either alone or in conjunction with surgical intervention (hemimandibulectomy).
Surgical
These include bone exposure, orocutaneous fistula, and failure of osteomyocutaneous flaps. Salvage procedures after RT are associated with an increased risk of complications. Damage to the lingual nerve or the hypoglossal nerve, although rare, is associated with difficulty in swallowing and/or speaking.
Radiation-Induced Bone Disease
The edentulous person is less likely to develop serious RT-induced mandibular damage than a person with teeth. The most frequent problem involving the mandible is a bone exposure. The gingivadisappears, exposing the underlying bone. If the exposed area is small, the patient is often unaware of the problem. If the patient has dentures, those dentures should be discontinued or altered to relieve the pressure over the exposed bone. If sharp bony edges appear, they are filed and the bone edge lowered to speed healing. Healing may require months or even years.
If ORN develops, hyperbaric oxygen has been used with some success. Conservative measures should be given a fair trial, but if unsuccessful, segmental mandibulectomy and an osteomyocutaneous flap reconstruction is performed.
Buccal Mucosa
Verrucous carcinoma accounts for <5% of all oral cavity
carcinomas, occurs most often in the buccal mucosa, has a
more favorable prognosis, and is considered a low-grade
malignancy. Surgical resection remains the preferred mode of
treatment for primary lesions of the buccal mucosa. Adjuvant
radiation treatment is usually not indicated. Since verrucous
carcinomas rarely metastasize, elective neck dissection is
often not indicated for patients with this disease.
Routes of spread
Squamous-cell carcinoma of the buccal mucosa can extend to
involve the pterygoid muscles, and superiorly, they can grow
to involve the alveolar ridge, palate, GBS, maxillary sinus,
mandible. The majority of patients have cancer that extends
beyond the buccal mucosa. Metastasis to the cervical lymph
nodes most commonly affects the submandibular nodes.
Lymph node metastasis occurs in approximately 9% to 31%
of the patients during the course of the disease. Involvement
of the upper cervical and the parotid lymph nodes is less
common.
Treatment
Selection of Treatment Modality
Small lesions (≤1 cm) may be excised with primary closure;small
lesions that involve the lip commissure or in the mid-cheek
without sulcus invasion are treated by RT. Lesions 2 to 3 cm in size
can be treated with surgery or by RT, usually the former. Transoral
resection is preferred and is most convenient for small lesions.
Larger lesions are usually treated with surgery (composite
resection of buccal mucosa with mandible or upper alveolus or
overlying skin) and postoperative RT or chemoRT. A recent
report stated that T classification and negative margins are not
adequate predictors of local control, and even early buccal tumors
could benefit from adjuvant therapy to enhance local control. In
another series, local recurrence occurred in all patients with stage
I and II disease treated with wide local.
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18
Surgery Tumors approximating the gingiva should be resected with the
gingiva and periosteum as an additional deep margin, while those that involve the periosteum should be resected with an additional deep margin of bone. Cancers that directly invade bone should be resected with a segment of bone.Repair may require a maxillary prosthesis. A myocutaneous flap repairs full-thickness removal of the cheek.
A radical neck dissection is recommended in all patients with a node-positive neck, whereas a supraomohyoid neck dissection can be considered in the node-negative neck.
Surgery is also considered in patients who recur after radiotherapy as salvage. One series reported a 5-year actuarial disease-free survival after surgical salvage of 59.7%.
Irradiation Technique
As in other sites of the oral cavity, adjuvant treatment with chemotherapy and radiation is recommended in patients with positive margins or extranodal extension. In cases that are inoperable, radiotherapy in combination with chemotherapy can be used.
Buccal mucosa lesions are suited for treatment with electrons, intraoral cone, and interstitial techniques to spare the contralateral normal tissues. When tumors extend into one of the gingivobuccal gutters or onto bone, treatment must be entirely by EBRT.
Intraoral device can be placed to displace & shield the tongue.
An ipsilateral mixed photon/electron beam ( or wedged photon pair) & a boost is given with brachytherapy or intraoral seeds.
Field borders: 2cm anterior & superior to the lesion ; posteriorlyat the posterior aspect of the spinous processes if nodes are to be irradiated; inferiorly at the thyroid notch.
The oral commissures & lips should be excluded or shielded if possible.
Postop volume include the tumor bed, scars, & ipsilateral IB & II nodes.
Patients with positive nodes receive B/L neck RT to the upper & lower neck.
Buccal Mucosa:
Indications:
Brachytherapy alone indicated for small (<4cm), well-defined
lesions in anterior 2/3rd
As boost after EBRT for larger lesions
T.V.: GTV + margins
Dose: Alone 65-70 Gy
Boost 25-30 Gy
Technique: Guide Gutter Technique: Lesion < 2cm
Plastic tube technique: For other lesions
Either 3-D conformal therapy or IMRT should be used to
spare the contralateral parotid gland. Because buccal mucosa
lesions are lateralized, treatment of the contralateral buccal
mucosa is not necessary in T1 and T2 lesions. Postoperative
dosing regimens for buccal mucosa cancer are similar to
other regions of the oral cavity.
doses of 66 Gy in 2-Gy fractions for positive margins, 60 Gy
in 2-Gy fractions or 59.4 to 63 Gy in 1.8-Gy fractions to
high-risk regions, and 54 Gy in 1.8-Gy fractions for low-risk
regions. An LAN is often used, treated to either 50 Gy in 2-
Gy fractions or 50.4 Gy in 1.8-Gy fractions.
Results of Treatment
Diaz et al. recently reported the M. D. Anderson experience for 119 patients treated with surgery alone (84 patients) or combined with adjuvant RT (35 patients) between 1974 and 1993. Tumor recurrence developed in 54 patients (45%): local recurrence in 27 patients (23%); regional recurrence in 13 patients (11%); local and regional recurrence in 11 patients (9%); and distant metastases in 3 patients (3%). The 5-year survival rates versus stage were stage I, 78%; stage II, 66%; stage III, 62%; stage IV, 50%; and overall, 63%.
A study by Lin and colleagues examined 121 patients with M0 disease treated with either surgery alone, radiotherapy alone, or surgery plus postoperative radiation. The rate of local recurrence in patients with T1-
2-N0 disease who received surgery alone was 40%, and for locally advanced disease both locoregional control and overall survival were improved in those patients receiving a combined-modality approach.[
Nair et al. reported the definitive RT results for 234 cases of buccalmucosa cancer treated in southern India during the 1982 calendar year. The 3-year disease-free survival rates were stage I, 85%; stage II, 63%; stage III, 41%; and stage IV, 15%. Thirty-two patients had verrucouscarcinoma; the 3-year disease-free survival rate was 47%, similar to that for other grades of SCC.
Complications of Treatment
The buccal mucosa is tolerant of high-dose RT, and
complications are uncommon. Bone exposure may appear on
the mandible or maxilla. Trismus may develop if the muscles
of mastication receive high doses.
Surgical injury of Stensen’s duct may cause obstruction and
parotitis. Injury to branches of the VII nerve may occur. Split-
thickness skin grafts may shrink and produce partial trismus.
Resection of the lip commissure may produce oral
incompetence.
Treatment Outcome
Reports of the select retrospective studies of carcinoma of
the buccal mucosa can be found in Table 29-6.A prospective,
randomized trial from India examined the role of
postoperative radiotherapy in stages III and IV carcinoma of
the buccal mucosa. The 3-year actuarial disease-free survival
was 68% versus 38%, with and without postoperative
radiotherapy. The 3-year actuarial overall survival was 94%
versus 84%, respectively.
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19
Hard Palate and Upper Alveolar Ridge
Initial growth tends to be superficial, although these tumors
can extend through the periosteum of bone into regions
adjacent to the oral cavity, such as the paranasal sinuses and
floor of the nose. Lymph node spread is present in less than
10% of patients.
Although radiation can be used to treat carcinomas of this
site, surgery is preferred. Postoperative radiation therapy
should be delivered when there are adverse features; that is,
close/positive margins, perineural extension, vascular
invasion, high-grade histology, multiple positive nodes, or
extracapsular extension.
Surgery
Maxillary antrum not involved: partial maxillectomy or RT in select T1-2 lesions.
Maxillary antrum involved: orbital floor preserving total maxillectomy with reconstruction.
A defect in the maxilla results in lack of oral/nasal separation that can impair the ability to speak and swallow effectively. An obturator ( synthetic polymer) with or without a skin graft is the most common method used to restore oral/nasal separation.
Regional pedicled flaps and free-tissue transfers may provide alternatives to obturation. However, their use is somewhat controversial for reconstruction of palatal defects since these nonremovable flaps may mask local recurrences that can be more readily identified in patients whose defects are obturated.
Elective treatment of the neck is controversial for hard palate
region tumors. Although some series have shown lower rates of
occult metastases for palatal tumors when compared to other oral
cavity sites, preoperative imaging should be performed to evaluate
for the presence of metastases to the retropharyngeal nodes since
these are difficult to evaluate on clinical examination and are at
some risk for spread from primary palatal tumors.
Ameloblastoma
The treatment for ameloblastoma is surgery; however, local
recurrence is a problem.
Limited experience with RT suggests that it may reduce the
probability of progression and result in long-term local control in
the occasional patient with incompletely resectable disease.
Very superficial lesions of the hard palate can be treated
definitively with surface molds. If definitive external-beam
radiation therapy is used with conventional techniques, the patient
is treated with opposed-lateral fields or wedge pairs to 66 to 74
Gy in 2-Gy fractions.
When IMRT techniques are used, a dose of 70 Gy is used for gross
tumor, 59.4 to 63 Gy for high-risk regions, and 54 Gy for low-risk
regions.
In the postoperative setting, doses of 60 to 66 Gy using 1.8 to 2
Gy per fraction are administered, with a dose of 66 Gy being
reserved for patients with positive margins. Postoperative
radiotherapy usually begins 2 to 3 weeks after surgery.
A prosthesis (i.e., obturator) can be placed over the postsurgical
defect during radiotherapy. Alternatively, a balloon filled with
water can be used to compensate for postsurgical tissue defects.
The radiation field
should encompass
the entire surgical
bed. In most cases it
is necessary to treat
with opposed lateral
fields to cover the
volume at risk.
However, for well-
lateralized lesions of
the upper alveolar
ridge, ipsilateral
radiation with a
wedge pair may be
adequate.
Treatment Outcome
Owing to the rarity of this disease, limited information is available.
Evans and Shah reported their 15-year experience from the Memorial
Sloan-Kettering Cancer Center. For stage I squamous cell carcinoma of
the hard palate, the 5-year disease-free survival rate was 75% (6/8); all
patients were treated with surgery alone. For stage II disease, 46%
(6/13) were disease free at 5 years; postoperative radiotherapy was
added in one patient. In stage III disease, the 5-year disease-free survival
rate was 40% (4/10); one patient in the group received postoperative
radiotherapy. In stage IV patients, 8% (1/12) of patients treated with
surgery alone, 25% (1/4) of those treated with radiotherapy alone, and
none (0/2) of those treated with the combined modality were disease-
free at 5 years. In another series of patients with squamous cell
carcinoma of the hard palate, from the University of Virginia, select
early-stage lesions were equally effectively treated by radiotherapy as
surgery during the supervoltage era. Patients with a clear margin after
surgical resection had improved local control. See Table 29-9 for select
results of definitive radiation therapy of the hard palate.
Carcinoma of the Upper Gingiva Routes of Spread Carcinomas of the upper gingiva usually
spread by direct invasion into the maxillary sinus or the upper gingivobuccal sulcus. Lymph node metastasis most frequently involves the submandibular lymph nodes. The subdigastric and upper cervical nodes are less frequently involved. At diagnosis, 18% to 52% of patients have positive lymph nodes.
Treatment Approach Because of early bone involvement and the risk of bone exposure after the tumor is irradiated, surgery is the treatment of choice for carcinomas of the upper gingiva. Except for early superficial lesions, most tumors of the hard palate and upper gingiva are treated with surgery. Postoperative radiotherapy is added in high-risk patients.
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For gingival lesions, if PNI is present, the entire hemimandible from mental foramen to the TMJ is treated
Fields cover the primary with 2 cm margins and the upper neck nodes. The low neck is treated for T3/4 or LN+.
Definitive RT for T1:60-66 Gy, T2: 66-70 Gy,T3-4:> 72 Gywithout chemotherapy & 70 Gy with chemotherapy.
Postop EBRT: 1.8-2 Gy/fx to 50-54 Gy f/b boost to 60 -66 Gy to high risk ares.
A balloon filled with water can be used to compensate for postsurgical tissue defects. Postoperative radiotherapy usually begins 2 to 3 weeks after surgery.
Treatment Outcome In the review of the Memorial Sloan-Kettering Cancer Center experience of 61 patients with upper gingival tumor treated mostly with surgery, the 5-year survival rate was 51% (31/61). Clinical stage was the only predicator of survival.In another series of 82 patients from Japan, the 5-year local control rate was 61% with a 5-year actuarial survival of 45%. A third more recent series from India examined the results of 110 patients with tumors of the superior gingival-buccal complex treated with either surgery alone, radiation alone, or a combined modality approach. Five-year progression-free survival was 49% for patients treated surgically and 0% with a nonsurgical approach. T stage and extracapsular spread were predictors of disease progression.
Carcinoma of the Lower Gingiva
Routes of Spread
Tumor spreads mainly through the occlusal ridge alone or in combination with penetration of the buccal or lingual plates in edentulous patients. Lymph node metastasis is present in 13% to 24% of patients with carcinoma of the lower gingiva. The submandibular lymph nodes are most frequently involved. Involvement of the subdigastric and upper cervical nodes is less common. Direct invasion of the mandible may be present in 50% of the patients on initial examination. The actual extent of bone involvement may exceed that shown on radiographs. Therefore, additional imaging is essential to accurate preoperative assessment.
Treatment Approach
Because of frequent bone involvement and lymph node
metastasis, surgery has been the primary treatment modality
in the management of carcinoma of the lower gingiva.
Early superficial lesions can be expeditiously treated by a
simple excision or marginal resection with skin graft.
Patients with advanced T stage, radiologic or histologic
evidence of mandibular invasion, tumors involving the
symphyseal region, and decreased tumor differentiation have
high propensity for regional metastases. Therefore, elective
treatment of the neck should be considered.
Mandible uninvolved or
minimally involved:
Mandible grossly involved
W/E with marginal mandibulectomy ( avoided in RMT disease, edentulous mandible, paramandibulardisease, post RT)
Indications of MM: tumor close to the mandible to achieve adequate margins ( 5-10 mm), limited superficial bony erosion, limited periosteal invasion.
W/E with segmental/ hemimandibulectomy with postoperative CT-RT
Indications of Segmental Mandibulectomy:gross tumor invadind the mandible, prior RT, edentulous mandible, gross paramandibular disease, whenever inferior soft tissue & bony margin of 1 cm is not possible( RMT, gross perioteal invasion)
Irradiation
In patients with more advanced disease, postoperative radiotherapy can reduce the incidence of local recurrence.
Early superficial lesions, less than 2 cm in diameter, can be adequately treated with 60 Gy using electrons in 3 to 4 weeks using a peroral cone.
Carcinomas that involve a large surface area with little or no bone invasion may be treated by EBRT. T1–T2 carcinomas are treated with altered fractionation; larger tumors are treated with combined EBRT and concomitant chemotherapy.
Orthovoltage energies should not be used over bone.
For more advanced unresectable disease, a definitive external-beam irradiation technique, preferrably with IMRT, should be used to a dose of 70 Gy.
If IMRT is not available and conventional techniques are being used, oblique- or right-angle, wedged-pair field arrangements can be used to spare the contralateral salivary glands.
Treatment Outcome
Local control of carcinomas of the lower gingiva treated with radiotherapy alone was achieved in 71.5% (5/7) of T1 lesions, 70% (7/10) of T2 lesions, 59% (10/17) of T3 lesions, and 29% (4/14) of T4 lesions in the series reported by MacComb.[92] The 5-year survival rate of 108 patients treated between 1947 and 1960 at the MD Anderson Cancer Center was 46%.[92] Most series report excellent local control with surgery followed by postoperative radiotherapy when indicated. Results from select series are shown in Table 29-7.[110],[113] In the aforementioned study at MD Anderson Cancer Center[112] examining prognostic factors of the disease, the authors found that advanced T stage, positive surgical margins, mandibular invasion, and cervical metastases were all associated with a worse overall survival.
Results of Treatment
Mandibular Gingiva
Overholt et al. reported 155 patients with SCCs of the lower alveolar ridge treated at M. D. Anderson between 1970 and 1990. Surgery alone was used for 131 patients and the remainder received surgery and RT. Five-year survival for patients with T1 and T2 cancers were 85% and 84%, respectively, compared with 66% and 64%, respectively, for those with T3 and T4 malignancies. Local control at 2 years was impacted by tumor size (P = .021) and margin status (P = .027), whereas 5-year cause-specific survival was influenced by tumor size (P = .001), margin status (P = .011), mandibular invasion (P <.05), and the presence of lymph node metastases (P <.001).
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Retromolar Trigone
Byers et al. reported the M. D. Anderson results for 110 previously untreated patients with SCC of the retromolar trigone treated between 1965 and 1977, with a minimum 5-year follow-up. Surgery was often selected for patients with leukoplakia, poor teeth, mandible invasion, large neck nodes, or trismus. RT was selected for poorly differentiated tumors, for mainly exophytic lesions, and lesions involving the faucial arch or soft palate, or lesions having ill-defined borders, and for patients who had poor surgical risk. The local control rates were as follows: T1, 12 of 13 (92%); T2, 50 of 57 (88%); T3, 18 of 20 (90%); and T4, 15 of 20 (75%). Local control was similar after surgery and/or RT. The absolute 5-year survival rate was 26%.
Mendenhall et al. reported on 99 patients with retromolar trigone SCCs treated between 1966 and 2003 with RT alone (35 patients) or combined with surgery (64 patients). The 5-year locoregional control rates after RT versus surgery and RT were stages I–III, 51% and 87%; stage IV, 42% and 62%; and overall, 48% and 71%, respectively. The 5-year cause-specific survival rates after RT versus surgery and RT were stages I–III, 56% and 83%; stage IV, 50% and 61%; and overall, 52% and 69%, respectively. Multivariate analysis revealed that the likelihood of cure was better after surgery and RT compared with definitive RT
Hard Palate
Shibuya et al.reported the results for 38 cases of carcinoma of the hard palate and 82 cases of carcinoma of the upper alveolar ridge treated between 1953 and 1982 in Japan. Sixty-six patients were managed initially by RT alone to the primary lesion, and 54 patients were managed by RT and surgery. The 5-year actuarial survival rate by stage was the following: stage I, 56%; stage II, 41%; stage III, 32%; and stage IV, 12%. There was no difference in survival when comparing hard palate versus upper alveolar ridge, SCC versus minor salivary gland tumors, or RT alone versus RT plus surgery as the initial therapy. The overall risk for metastatic lymph nodes was 47% for hard palate and 49% for the upper alveolar ridge. Thirty patients were recorded as having “slight bone invasion” and no metastases and had a 5-year survival rate of 75% when treated by RT.
Complications of Treatment
Surgical complications include orocutaneous fistula, bone
exposure, extrusion of a metal tray, and loss of graft or flap.
Following hemimandibulectomy, the edentulous patient
usually cannot wear dentures.
The complications of RT include soft tissue necrosis, bone
exposure, and ORN. The risk is greatest for patients with
advanced lesions of the lower gum and retromolar trigone.
Huang et al. reported the following rates of grade 3 bone and
soft tissue complications in 65 patients treated for retromolar
trigone carcinomas: preoperative RT, 0 of 10 patients (0%);
surgery and postoperative RT, 5 of 39 patients (13%); and RT
alone, 2 of 16 patients (13%).
Retromolar Trigone
Cancers of the retromolar trigone may be advanced at
presentation because only a thin layer of soft tissue overlies
the bone in this region and invasion of the underlying bone
may occur early. In addition, there are multiple pathways for
spread from this site including the buccal mucosa, tonsillar
fossa, glossopharyngeal sulcus, floor of the mouth, base of the
tongue, hard and soft palate, masticator space, and maxillary
tuberosity.
Frequently metastasize to the subdigastric lymph nodes. The
submandibular and upper cervical lymph nodes are affected
less often. The incidence on diagnosis is approximately 30%.
Early stage T1 and T2 cancers can be treated equally effectively with surgery or radiation with primary control rates for T1 and T2 tumors of 92% and 88%, respectively.
For more extensive superficial lesions that extend to involve the soft palate or tonsillar complex but do not invade bone, radiotherapy may be a better treatment option, since broad resection of the palate can result in poor speech and swallow outcomes.
Well-lateralized lesions of the retromolar trigone can be treated by ipsilateral mixed beam techniques or angled wedge techniques.
Stage III and IV lesions commonly require combined surgery and radiation. A limiting factor for the achievement of adequate surgical resection margins for tumors in this area includes extension of tumor posterosuperiorly into the pterygopalatinefossa and into the base of skull.
When external-beam irradiation is used alone with conventional methods, a technique using mixed electrons and photons with single lateral fields or parallel opposing fields with 2 : 1 weighting favoring the side of the disease can be used. Usually a dose of 66 to 74 Gy in 2-Gy fractions is administered.
IMRT can be used when available, using a dose of 70 Gy for gross disease, 59.4 to 63 Gy for high-risk disease, and 54 Gy for low-risk disease.
Prophylactic treatment of the neck is essential as lesions located in the retromolar trigone have a high propensity for metastases in the neck. We generally treat the contralateral lymph node levels I through V electively in patients with T3, T4, or node-positive disease, whether in definitive treatment or in the postoperative setting.
(Fig. 29-19).
T4N0
Retromolar Trigone
(Postoperative)
Treatment Outcome MD Anderson Cancer Center reported results of 159 patients
with squamous cell carcinoma of the anterior faucial pillar and retromolar trigone region treated with radiation.[114] Local control with radiation alone for T1 lesions was 71% (12/17); for T2lesions, 70% (51/81); for T3 lesions, 76% (19/25); and three of five T4 lesions were controlled. Most of the failures were treated with surgery, and the ultimate control rate was 100% for T1, 94% for T2, and 92% for T3. The overall N0 neck failure rate was 11%. The authors recommend elective treatment of subdigastric and upper jugular nodes to the level of the hyoid. The 5-year determinate survival rate in the series was 83%. A more recent study at the Notre-Dame Hospital in Quebec demonstrated 5-year regional control rates of 88% after definitive radiation and 67% after salvage surgery.[115] See Table 29-8 for select results of treatment for carcinoma of the retro molar trigone.[115-117]
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Management of Recurrent Disease The appropriate management of recurrent oral cavity cancer
depends largely on the extent of disease, the prior therapy administered, and whether the recurrences are local, regional, or both. Obviously, if there is distant disease recurrence, systemic therapy approaches will likely assume primary importance. In the case of small recurrences at the primary site for patients treated with primary excision only, further excision with or without postoperative radiotherapy is often recommended. For larger recurrences in patients who received radiation as part of their initial management, the rate of surgical salvage is quite low. In some cases, further resection may be considered for palliation or curative treatment attempt, particularly in the setting of a clinical trial. Systemic therapy, reirradiation, and palliative care are other options for this group of patients, and the risks and benefits of each should be discussed with the individual patient.
Critical Normal Tissues
Acute and Late Effects Acute changes occur in the oral mucosa, the
salivary glands, and the taste buds during irradiation. Unless the
parotid glands are blocked or constrained, xerostomia occurs after a
few weeks.
With 3-D conformal treatment or IMRT, the restoration of at least
partial salivary function can be effectively accomplished with
appropriate limits. Dosimetric sparing of the parotid glands during
IMRT in head and neck cancer, defined by a mean parotid dose, less
than or equal to 26.5 Gy, is feasible when the parotid–planning target
volume overlap is less than 20%.
Acute mucositis cannot be avoided. For the definitive treatment of
lesions with radiotherapy, the goal is to achieve mucositis that is either
patchy (grade 2) or confluent (grade 3).
Xerostomia✓ Radiation > 3000 cGy
✓ Starts after 1 wk of treatment
✓ Dose related
✓ Saliva flow reaches ‘zero’ with 6000 cGy
✓ Serous acini affected more than mucous acini
✓ May resolve within 6 months
✓ If persisted for more than 1 yr, permanent damage
Management
Sialogogues
Pilocarpine
Bethanecol
Prophylactic
- Pilocarpine, Amifostine ( not used)
MucositisWith common fractions of 180 to 220 cGy per day, mucositis with erythema is
noted in 1 to 2 weeks and increases throughout the course of therapy -to a maximum in 4 weeks- with persistence until healing occurs 2 or more weeks after the completion of therapy.
Management
-Systemic
(1) Pain management
- Analgesics: WHO ladder
- Adjuncts: Relaxation, imagery, biofeedback, hypnosis and transcutaneous electrical nerve stimulation
- b carotene
(2) Radioprotectors
- Amifostine: Scavenge free radicals
(3) Biologic Response Modifiers
- G-CSF, GM-CSF, Keratinocyte Growth Factor
Topical Diluting agents
Saline, bicarbonate rinses, frequent water rinses, dilute hydrogen peroxide rinses
Coating agents
Kaolin-pectin, aluminum chloride, aluminum hydroxide, magnesium hydroxide, hydroxypropyl cellulose, sucralfate
Lip Lubricants
Water-based lubricants, lanolin
Topical anesthetics
Dyclonine HCl, xylocaine HCl, benzocaine HCl, diphenhydramine HCl
Analgesic agents
Benzydamine HCl
Late effects are seen as bone necrosis in the mandible and the maxilla, which occurs after breakdown of the mucosa and exposure of the bone with ensuing osteomyelitis.Teeth in poor condition should be extracted prior to radiation therapy. The teeth must be maintained in good condition to avoid extractions, which can lead to infection. Soft-tissue necrosis is frequently seen after both brachytherapy and peroral cone treatment. It is painful, but usually heals without surgery. A necrotic mandible often must be resected.
With the advent of IMRT, there appears to be a reduction in the toxicity associated with treatment of the oral cavity. A study from the University of Michigan demonstrated no cases of osteoradionecrosis in 176 patients treated with head and neck cancer from 1996 to 2005 with at least 6 months of follow-up.Of these patients, 75% received greater than or equal to 65 Gy to at least 1% of the mandibular volume, and 50% had received at least 70 Gy to this volume. However, the authors found a high level of falloff across the mandible, with the average gradient being 11 Gy.
Dental and Oral Care After radiotherapy, there is increased
susceptibility to infection and development of dental caries. This is
due to the decreased amount and pH of the saliva, diminished
vascular supply, reduced number of osteoblasts and osteoclasts,
altered normal metabolism of bone, and impaired ability to heal in
response to physical, chemical, and biologic injuries after head and
neck irradiation. As a result, osteoradionecrosis develops in
patients following head and neck irradiation, especially if proper
preradiotherapy dental care was not done. The mandible is most
commonly involved and the maxilla is rarely affected. The risk of
osteonecrosis is directly related to the radiation dose to the bone.
The incidence and severity of dental decay and osteonecrosis can
be minimized with proper dental care and hygiene before, during,
and after head and neck irradiation.
During radiotherapy, patients are encouraged to irrigate the
mouth with a salt and baking soda solution (1/2 to 1 teaspoon of
salt and 1/2 to 1 teaspoon of baking soda in 1 quart of warm
water) three to four times daily. Moniliasis is a common
complication during irradiation of the head and neck. This can be
effectively controlled with systemic antifungal agents. Once the
patient has been placed on an agent, it is important to maintain its
use until the completion of radiotherapy. Otherwise, moniliasis
usually recurs if treatment is discontinued during the course of
radiotherapy.
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After radiotherapy, the patients are continued on a good oral hygiene program and topical fluoride applications (mouth rinses) as well as a fluoride-containing dentifrice. Caries are filled and there are no unusual contraindications for endodontic procedures. Extractions are performed whenever necessary and antibiotics are routinely used to minimize the risk of infection. When osteonecrosis develops, it is usually managed conservatively with topical or systemic antibiotics and analgesics initially. Good oral hygiene is imperative. Loose spicules of bone above the gingival crest are gently removed. Healing may take place over a period of several months. Partial mandibulectomy is performed only if conservative management fails and the patient continues to have persistent pain, infection, or trismus.
Dietary supplements such as instant breakfast, Sustagen, Ensure, or other homemade substitutes are soothing to the mucosa and easy to swallow, and provide a substantial amount of calories as well as essential vitamins.
In patients with severe pain and dysphagia or problems of mastication or excessive weight loss, tube feeding may be necessary. The aim of a dietary program during head and neck irradiation is to provide adequate nutrition and prevent weight loss. Percutaneous gastrostomy tube placement may be required for patients who lose more than 10% of their body weight. Multiple studies have shown that prophylactic gastrostomy tubes are safe and may limit weight loss in patients receiving radiation for head and neck cancer, and we strongly consider their placement, particularly in patients receiving chemotherapy in conjunction with radiation.
Follow up History and physical exam :
Year 1, every 1–3 mo
Year 2, every 2–4 mo
Years 3–5, every 4–6 mo
> 5 years, every 6–12 mo
Post-treatment baseline imaging of primary (and neck if treated) recommended within 6 mo of treatment (category 2B)
Further reimaging as indicated based on signs/symptoms; not routinely recommended for asymptomatic patients
Chest imaging as clinically indicated
Thyroid-stimulating hormone (TSH) every 6-12 mo if neck irradiated
Speech/hearing and swallowing evaluation and rehabilitation as clinically indicated
Smoking cessation and alcohol counseling as clinically indicated
Dental evaluation