seroma volume changes
TRANSCRIPT
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Presented by Wesley Zoller, B.S.R.T.(T) Medical Dosimetry Student June 19th, 2013 AAMD Annual Meeting San Antonio, TX
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A Little Background on Me
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I’m a Country Fella from Churchtown, Ohio
• Small little farming community by the Ohio River
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My Family!
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B.S.RT(T) from the Ohio State University (2012)
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Cleveland Browns Fan…..
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Honorary Spurs Fan for these few weeks…
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Student in the Cleveland Clinic CMD Program
• Graduating July 19th, 2013!!!!
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When I have time, I like to do a little golfing…
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Presented by Wesley Zoller, B.S.R.T.(T) Medical Dosimetry Student June 19th, 2013 AAMD Annual Meeting San Antonio, TX
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Aims of the Study
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Objectives
• Quantify the changes in seroma volume over the course of RT for early stage breast cancer patients eligible for RTOG 1005.
• Evaluate the dosimetric impact of these changes on sequential boost planning in accordance with Arm I of RTOG 1005.
• Assess the need for adaptive planning and pre-boost CT acquisition for sequentially boosted breast cancer patients based on evaluation with RTOG 1005 criteria.
• Dosimetrically compare two hypofractioned boost methods, concurrent electron versus concomitant tangential IMRT photon, with the planning/evaluation criteria outlined in Arm II of RTOG 1005.
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Background of RTOG 1005
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Reference 1 on Final Slide
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Reference 1 on Final Slide
• For Early Stage Breast Cancer Patients (Stage I-II)
• Post-Lumpectomy Breast Conservation Course
• Shorten Treatment Time
• Objectives of Study
• Primary: determine if accelerated hypofractionated WBI with concomitant tumor bed boosting is non-inferior in local control to Standard of Care sequential boost and fractionation scheme
• Secondary: determine if ARM II is non-inferior to the Standard of Care in terms of cosmesis, treatment symptoms (3 weeks and at 3 years), cardiac toxicity for left sided cases, and treatment costs
• If non-inferior, determine if ARM II hypofractionated scheme is superior to Standard of Care fractionated in same criteria
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Previous Literature
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• 2009 study, aimed to evaluate the change in seroma volume over WBRT prior to boost planning.
• 24 patients with evident seroma on initial CT, received 42.4Gy/16fx with 9.6Gy/4fx boost or 50.4Gy/28fx WBRT with 10Gy/5fx boost
• Second CT acquired at 3-5 weeks, dependent upon fractionation schedule
• Mean CT1 seroma was 65.7 cc and CT2 was 35.6 cc. Mean reduction of 39.6% with an SD of 23.8%, p<0.001, 2 of 24 patients showed increase in size with an increase or 9.7% and 10.7%
• Changes during WBRT found to be significant and group concluded boost planning accuracy can be affected by these changes.
Reference 6 on Final Slide
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Reference 7 on Final Slide
• 2009 study, aimed to determine if lumpectomy cavity decreases in volume during whole breast radiotherapy and contributing factors.
• 43 patients, 44 breast lesions prospectively enrolled. Lumpectomy and CT sim within 60 days of surgery. WBRT 45-50.4 Gy.
• CT2 acquired b/w 21-23 treatments, seroma contoured on new CT and compared.
• Mean volume was 38.2 cc on CT1, 21.7 cc on CT2. Mean decrease of 32% and 11.2 delta cc. Decreased on 38 of 44 patients (86%), p<0.001
• Concluded that tracking change and acquiring a pre-boost CT can lead to decreased doses of radiation to remaining breast and critical structures, and should be considered in patients with larger cavities.
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Methods
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Summary of Methods
• 11 early stage breast cancer patients eligible for RTOG 1005
• Clinically evident seroma at time of initial simulation (CT1)
• Received second CT (CT2) prior to planning of sequential boost
• Seroma volume/Lumpectomy GTV delineated on both datasets
• PHASE I: Characteristics of both CT1 and CT2 seroma volumes recorded
• Fusion of CT2 dataset and contour onto CT1 dataset
• In accordance with RTOG 1005 Arm I, patients retrospectively re-planned giving 50Gy/25fx to whole breast and boosting sequentially with 12Gy/6fx given via electron boost to the cavity (Standard of Care Arm)
• Boost plans individually optimized for each volume (CT1 vs. CT2)
• Plans compared based on dose to Heart, Ipsilateral Lung, Breast PTV Eval (Normal Breast), and coverage of Lumpectomy PTV Eval using specified Arm I evaluation criteria
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Summary of Methods
• PHASE II: Comparison of Concurrent Hypofractionated Boost Methods
• In accordance with RTOG 1005 Arm II, patients retrospectively re-planned giving 40Gy/15fx to whole breast tangents and boosting concurrently with 8 Gy in the same 15 fx
• Boost plans individually optimized for CT1 target volumes
• Concurrent Electron Cavity Boost
• Concomitant IMRT Photon Cavity Boost
• Plans compared based on dose to Heart, Ipsilateral Lung, Breast PTV Eval (Normal Breast), and coverage of Lumpectomy PTV Eval using specified Arm II evaluation criteria
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Contouring for the Study (Using RTOG 1005 Delineation Guidelines)
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Lumpectomy GTV (per RTOG 1005) • Excision cavity volume, architectural distortion, lumpectomy scar,
seroma and/or extend of surgical clips (clips strongly recommended)
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Lumpectomy CTV (per RTOG 1005) • Lumpectomy GTV + 1 cm 3D Expansion, Limiting Borders: Pectoralis
and Serratus Anterior Muscles, Midline, and 5 mm from skin surface
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Lumpectomy PTV (per RTOG 1005) • Lumpectomy CTV + 7 mm uniform 3D Expansion (Excluding Heart)
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Lumpectomy PTV Eval (per RTOG 1005) • Lumpectomy PTV minus area outside of ipsilateral breast, first 5 mm
of skin, and the chest wall/pectoralis muscles/lungs.
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Breast PTV Eval (per RTOG 1005) • Breast CTV (palpable breast volume – CW and 5mm skin) + 7 mm PTV
expansions in same Manner as Lumpectomy PTV Eval (avoid CW, 5mm)
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Critical Normal Structures (per RTOG 1005) • In this study: Ipsilateral Lung, Heart (Split of Pulmonary trunk into
Pulmonary Arteries superiorly to apex inferiorly), and Contralateral Lung.
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Image Fusion
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GTV Delineation (RTOG 1005) and Image Fusion
CT1 GTV Delineation CT2 GTV Delineation
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GTV Delineation (RTOG 1005) and Image Fusion
Box-Based Fusion using chest wall and Ipsilateral Breast
CT-CT Fusion done in PhilipsTM Pinnacle® SyntegraTM
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Evaluation/Results of Seroma Volume Changes CT1 versus CT2 Volume
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Results – Table 1 Seroma Volume Changes
Max Percent Decrease = 77.3%
Min Decrease = 46.1%
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Planning for Phase I: Sequential Electron Boost for CT1 and CT2 (RTOG Arm I)
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Phase I of Study, Sequential Boosting (Arm I)
• 11 patients, retrospectively re-planned for 50 Gy in 25 fractions tangentially to the whole breast.
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• Sequential Electron boosts given 12 Gy in 6 fractions to Lumpectomy GTV using Lumpectomy PTV as Block Margin
• Optimized for both CT1 and CT2 Scans for the 11 patients (Available MEV 6, 9, 12, 15, 18, 21)
Phase I of Study, Sequential Boosting (Arm I)
Boost BEV for CT1 Volume Boost BEV for new CT2 Volume
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Evaluation of Sequential Boost (RTOG Arm I) Phase I: CT1 versus CT2 Seroma Volume
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V58.9 of Lumpectomy PTV Eval >/= 95% (Arm I)
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V47.5 of Breast PTV Eval >/= 95% (Arm I)
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V56 of Breast PTV Eval </= 50% (Arm I)
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V62 of Breast PTV Eval </= 30% (Arm I)
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V20 of Ipsilateral Lung </= 20% (Arm I)
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Mean Heart Dose < 500 cGy (RTOG 1005 Arm I)
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Results for Sequential Boost (RTOG Arm I) Phase I: CT1 versus CT2 Seroma Volume
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Comparison (Phase I)
For Phase I, the lung and heart dose are comparable for both plans.
However, V56 of Breast PTV Eval drops by 6.8% for boost plan optimized to new volume
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Phase I of Study, Sequential Boosting (Arm I) • Comparison of Sequential Electron Boosts
Boost Plan for Lumpectomy PTV Eval CT1 Boost Plan for Lumpectomy PTV Eval CT2
Reduced V56 for Re-CT Optimized Plan
59.8 Gy
56 Gy
47.5 Gy
20 Gy
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Results - Table 2 for Sequential Boost (Phase I)
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Comparison of V58.9 of Lumpectomy PTV Eval
Old Plan still maintains coverage of re-scan Lumpectomy PTV Eval
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Planning for Phase II: Hypofractionated Concurrent Electron versus Concomitant IMRT Photon (RTOG Arm II)
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Phase II of Study, Hypofractionated Course with Concurrent Boosting (Arm II) • 11 patients, retrospectively re-planned for 40 Gy in 15 fractions
tangentially to the whole breast.
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Phase II of Study, Hypofractionated Course with Concurrent Boosting (Arm II)
• Concurrent Electron Boost (Same blocking as Initial Sequential Phase I) given concurrently 8 Gy over 15 fractions for 11 patients
• 8 Gy Concomitant IMRT Photon Boost “mini-tangents” for same 11 patients
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Evaluation of Concurrent Boost on Hypofractionated Course (RTOG Arm II) Phase II: Electron versus Concomitant IMRT Photon
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V45.6 of Lumpectomy PTV Eval >/= 95% (Arm II)
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V38 of Breast PTV Eval >/= 95% (Arm II)
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V44.8 of Breast PTV Eval </= 50% (Arm II)
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V48 of Breast PTV Eval </= 30% (Arm II)
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V16 of Ipsilateral Lung </= 20% (Arm II)
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Mean Heart Dose < 400 cGy (RTOG 1005 Arm II)
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Results for Concurrent Boost on Hypofractionated Course (RTOG Arm II) Phase II: Electron versus Concomitant IMRT Photon
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For Phase II, the ipsilateral lung and heart dose are comparable for both plans.
However, V44.8 of Breast PTV Eval dropped by 28.1% for Electron Boost vs. IMRT Photon Boosts
Comparison (Phase II)
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45.6 Gy
44.8 Gy
38 Gy
16 Gy
Phase II of Study, Concurrent Hypofractionated Boosting (Arm II)
Much higher V44.8 for Concomitant IMRT Photon Boost Plan
Concurrent 8 Gy Electron Boost Concomitant 8 Gy Photon IMRT Boost
• Comparison of Boost Methods
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Results - Table 3 for Hypofractionated Concurrent Boost (Phase II)
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Discussion
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Discussion
• Average seroma volume decrease of 57.1% +/- 8.96% from CT1 to CT2
• Time elapsed between CT acquisition was 33.6 days +/- 5.1 days
• ARM I SEQUENTIAL: V56 for Breast PTV Eval decreased by an average of 9.2% +/- 3.3% by optimizing the boost plan on a 2nd CT for the current standard of care WB + Boost (50 Gy + 12 Gy Boost)
• Lung and Heart Dose discrepancies were minimal b/w plans
• Coverage of Lumpectomy PTV Eval CT2 volume maintained using CT1-optimized plan
• Under-treating not found to be a concern in this study
• ARM II Hypofractionated: V44.8 for Breast PTV Eval decreased by an average of 16.2% +/- 8.1% on all Electron Boosts when compared to concomitant IMRT photon boost methods
• Lung and Heart Dose discrepancies were minimal b/w plans
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Discussion
• Findings showed significant dose differences to the Breast PTV Eval
• Reduced by re-planning sequential boost using pre-boost CT
• Reduced using electron boost versus IMRT photon
• Significance of findings?
• Beyond WB prescription, breast tissue deemed to be normal tissue
• Reducing amount of normal breast tissue in boost field could potentially decrease some of the acute side effects associated with treatment of the site4,5
• Potential also exists to reduce late effects from breast irradiation, such as the development of fibrosis4,5
• RTOG 1005 does not currently allow planning from a pre-boost CT
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• 2008 trial to investigate predictors of long-term risk of fibrosis
• Between 1989 and 1996, 5318 patients receive 50 Gy/25 fx WBRT
• 2661 not boosted, 2657 boosted w/ 16 Gy/8fx with electrons to tumor bed
• Median Follow-up 10.7 years in both, 1079 pt (20.8%) had developed moderate or severe fibrosis, 482 (9.3%) local recurrences, and 1013 (19.6% ) died
• Development dataset: 26.9% in boost arm had moderate or severe fibrosis versus 12.6% in non-boosted
• Boost reduced the risk of local recurrence by 41%
Reference 4 on Final Slide
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Conclusions
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Take Home Message • Breast volume beyond tangential prescription should be treated as normal
tissue and should be spared as much as possible
• Potential to minimize both acute and late RT effects
• Adaptive Planning, or optimizing using a pre-boost CT showed to significantly decrease excess irradiation to normal breast tissue
• Electron cavity boosting also showed to be significantly superior to photon mini-tangents
• Lung and Heart dose discrepancies minimal between respective comparisons
• Simply acquiring one CT and adaptively optimizing a new boost plan has the potential to significantly decrease excess dose to normal breast tissue
• 4th or so week of treatment, ample time for dosimetry to generate boost plan
• In a world of CBCT and IGRT, the simple acquisition of one additional CT may be considered worthwhile in terms of potential to better patient outcomes
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References and Co-authors of Manuscript
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Thank you all so much for your time and your attention!!!
Have a great afternoon and everyone travel home safely!!!