habibtm endoblate endoscopic radio frequency ablation in colorectal cancer
TRANSCRIPT
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AbstractPURPOSE: There are a number of alternative approaches to palliate cancers of the rectosigmoid, which may not
be well tolerated or produce effective symptom relief. Therefore, there is a continuing need to develop alternative
techniques for palliation. This paper reports our initial assessment of a new bipolar radiofrequency probe
(Endoblate™).
METHODS: Twelve patients with rectosigmoid tumors were treated with Endoblate™ during transanal
endoscopic microsurgery. In ten patients, this was followed by surgical resection and two patients were treated
with Endoblate™ alone. This study was designed to assess the technical utility of the device, immediate
complications, and histologic effect.
Endoscopic Radiofrequency Ablation in Colorectal Cancer: Initial ClinicalResults of a New Bipolar Radiofrequency Ablation Device
Keywords: Radiofrequency ablation, Rectosigmoid, Cancer,Endoluminal
DOI: 10.1007/DCR.0b013e31819a3e09
ISSN: 0012-3706
Accession: 00003453-200902000-00029
Full Text (PDF) 1369 K
Author(s):
Vavra, Petr M.D.1,2; Dostalik, Jan M.D.2;
Zacharoulis, Dimitris M.D.1,3; Khorsandi, Shirin E.
M.D.1; Khan, Shahid A. M.D.1; Habib, Nagy A.
M.D.1,4
Issue: Volume 52(2), February 2009, pp 355-358
Publication Type: [TECHNICAL NOTES]
Publisher: © The ASCRS 2009
Institution(s):
1 Department of Biosurgery and Surgical
Technology, Imperial College London, London,
United Kingdom
2 Department of Surgery, University Hospital
Ostrava, Ostrava, Czech Republic
3 Department of Surgery, University Hospital of
Larissa, Larissa, Greece
4 EMcision Ltd, London, United Kingdom
Endoblate™ was provided free of charge by
EMcision Ltd., London, United Kingdom.
Presented at the meeting of the Association of
Surgeons of Great Britain and Ireland,
Bournemouth, United Kingdom, May 14 to 16,
2008.
Address of correspondence: Nagy A. Habib, M.D.,
Head of Biosurgery and Biotechnology, Imperial
College, Hammersmith Hospital, Du Cane Road,
London W12 0NN, United Kingdom. E-mail:
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RESULTS: There were no technical problems. In the patients who had resection of the tumor immediately after
ablation (n = 10), there were no local complications evident at surgery. Histology of the resected specimens showed
that, on average, 82 (range, 60-99) percent of the tumor mass was destroyed in the ablation zone. In the remaining
two patients, Endoblate™ alone was used successfully to stop bleeding from the tumor.
CONCLUSIONS: These preliminary results illustrate the evolution and endoscopic application of bipolar
radiofrequency technology. Endoblate™ showed potential as a useful and safe tool for the palliation of lower
gastrointestinal malignancy.
The ideal management of patients with rectal or low sigmoid colon cancers is surgical resection; however, in 20
to 30 percent of patients, local tumor advancement, metastatic disease, or patient's comorbidity, prevent curative
resection from being undertaken.1 As the local disease progresses, these patients often need palliation of
symptoms, such as bleeding, obstruction, rectal urgency, or tenesmus, to improve their quality of life. A number of
different endoscopic techniques have been used to palliate tumors of the rectosigmoid, such as
neodymium:yttrium-argon-garnet (Nd:YAG) laser vaporization, argon plasma coagulation, electrocoagulation, and
cryotherapy.2,3 Alternatively, in selected patients, endoscopic metal stents can be used for long-term palliation.These alternative therapies, as well as palliating symptoms, may then be combined with systemic chemotherapy or
radiotherapy to further aid in local tumor control, as well as to provide additional symptom palliation.4
During the last decade, there has been a major interest in using radiofrequency (RF) energy to destroy solid
tumors in situ,5 with RF ablation becoming a standard therapeutic option for primary and secondary cancers of the
liver, when surgery cannot been undertaken.6-8 This approach to cancer management is a rapidly expanding field,
with the total number of thermal ablation procedures performed in the United States predicted to grow from an
estimated 47,600 in 2005 to 135,000 procedures in 2010.9 Endoscopic RF ablation has not been used previously for
the palliation of colorectal cancers. This study reports our initial experience of the endoscopic application of a
novel bipolar RF probe in the ablation of low rectosigmoid tumors, focusing on the device's technical utility,
immediate complications, and histologic effect.
PATIENTS AND METHODS
Description of Device and Operative Procedure
Endoluminal ablation of rectosigmoid tumors was performed with a newly designed bipolar RF probe
(Endoblate™, EMcision Ltd., London, United Kingdom). The only financial support from the manufacturer was that
the devices were provided free of charge. The device consists of three contact electrodes and one ring electrode,
which is activated by bipolar RF energy, so that no grounding pads need to be applied to the patient (Fig. 1). The
probe can be used with two alternative RF generators: Radionics Cosman Coagulator CC-1 or RITA 1500. The probe
is designed to be introduced through the working channel of an endoscope or via an operating proctoscope during
transanal endoscopic microsurgery (TEM). In the present study, all Endoblate™ sessions were performed during TEM
under general anesthesia.
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FIGURE 1. Close-up of the Endoblate™ probe.
The Endoblate™ catheter was introduced through the instrument channel of the operating proctoscope during
TEM (Fig. 2), ensuring that the three contact electrodes were in the retracted position. Under endoscopicvisualization, the distal tip of Endoblate™ was advanced so that the end of the device lay in contact with the area
of tumor to be treated. Using the handle mechanism of Endoblate™, the electrodes were advanced into the tumor
to a depth of 2 to 3 mm. The RF generator was then activated and power output was kept as low as possible to
achieve therapeutic effect, initially 1 watt (W), increasing to 4 W, if required. The RF energy was delivered to the
target area of the tumor, until an impedance increase of 10 percent was observed, indicating that in the target
tumor area, sufficient coagulation had been produced. The RF generator was then placed in standby mode and the
three electrodes of Endoblate™ retracted. Endoscopic ultrasound (EUS) was then performed to assess depth of
ablation in relation to tumor thickness, to minimize the risk of perforation during the procedure. After each
application of Endoblate™, a well-demarcated ablation zone was visible endoscopically and the probe was reapplied
step by step to produce a confluent area of RF ablation (Fig. 3).
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FIGURE 2. Endoblate™ catheter being introduced through the instrument channel of the operating proctoscope
during transanal endoscopic microsurgery (TEM).
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FIGURE 3. Transanal endoscopic microsurgery (TEM) showing the Endoblate™ probe being applied to a rectal tumor
to produce ablation.
When technically feasible, the ablated tumor was then resected at open or laparoscopic operation. This
allowed both immediate (intraoperative) assessment of the local complications and subsequent histologic
assessment of Endoblate™ to be performed.
Patients
The application of Endoblate™ was assessed in 12 patients with lower rectosigmoid malignancies. All patients
underwent preoperative assessment of their disease (history, clinical examination, and relevant investigations).
Patients selected for inclusion in this study had a tumor of the rectosigmoid and had given informed consent. The
decision not to perform curative or palliative resection after tumor ablation was based on the patient's fitness to
tolerate a surgical resection. In each case, suitability for the use of Endoblate™ for ablation alone or ablation
followed by surgical resection was discussed at a multidisciplinary team meeting. Local ethics approval wasobtained and the Declaration of Helsinki was adhered to throughout.
Data collected for each patient included tumor details (TNM staging) and level of fitness using the American
Society of Anesthesiology classification (ASA). Before ablation, EUS of the tumor was performed to document its
thickness and length. Procedural data collected included power requirements (W), procedure time (defined as the
time from insertion of the endoscope to completion of ablation), and ablation time (time from insertion of the
ablation catheter to its removal). Any Endoblate™ related complications were recorded and all patients were
followed up three weeks after the procedure with a full clinical assessment.
RESULTS
Patient Demographics, Tumor Characteristics, and Procedural DataTwelve patients (median age 70.4 (range, 54-82) years) were treated with Endoblate™. One patient underwent
tumor ablation on two occasions for palliation of bleeding. Table 1 summarizes the clinicopathologic characteristics
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of the treated patients.
TABLE 1. Clinicopathologic data for patients treated with Endoblate™
On endoscopic ultrasound assessment of the tumor before ablation, the median distance of tumors from the
anal verge was 7.2 (range, 0.7-15) cm, the median tumor thickness was 3.1 (range, 2.3-4.1) cm, and the median
tumor length was 4 (range, 3-6) cm. The mean total procedure and ablation time were 40 (range, 11-65) minutes
and 17 (range, 1-45) minutes, respectively. The average power setting used for ablation was 2.7 (range, 1-4) W.
Endoblate™ Procedural Morbidity and MortalityUnder the same general anesthestic, surgical resection was performed after endoluminal ablation in ten
patients. Only two patients were managed by endoluminal ablation alone to manage the symptom of bleeding. In
one of these latter patients, a planned repeat Endoblate™ treatment was performed 20 days after the initial
session.
Surgical procedures undertaken were TEM (n = 3), abdominoperineal excision (n = 3: 2 laparoscopic and 2
open), and anterior resection (n = 4: 2 laparoscopic and 2 open). At operation, there was no evidence of transmural
thermal injury, pericolic fluid, or any other adverse findings, such as bowel perforation, after endoluminal ablative
therapy. On macroscopic inspection of the resected specimen, the ablation zone was sharply demarcated from
tissue where no ablation had been performed.
No patient required a blood transfusion, and there was no endoluminal ablation treatment-related mortality or
morbidity during inpatient stay or during the three weeks of follow-up after discharge. In relation to the operative
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procedures undertaken, there were two complications: one wound infection and one pneumonia. Overall, the
median length of stay was 8.4 (range, 3-12) days. In the two patients who underwent ablation only, the average
length of stay was 3.5 days.
Follow-Up Data
Histologic assessment of the resected specimen after Endoblate™ therapy showed that, on average, 82 (range,
60-99) percent of the tumor mass was destroyed in the ablation zone (Fig. 4). In the two patients who had only
been treated with Endoblate™ (for the symptom of bleeding) and not undergone surgical resection, there were no
delayed complications relating to endoluminal RF ablation, nor were there any recurrent symptoms of bleeding at
clinical assessment three weeks following discharge.
FIGURE 4. Hematoxylin and eosin stain (magnification ×20) of resected rectal tumor after ablation showing the
histologic effect of Endoblate™ on the rectal tumor. An area of demarcation necrosis has been produced by
Endoblate™, which lies to the right of the marked line, highlighted by an asterisk.
DISCUSSIONVarious strategies, such as diverting colostomy, radiotherapy, chemotherapy, self-expanding metal stents, and
endoscopic ablative therapy, have been used to palliate tumors of the rectosigmoid.1-4 These approaches are not
always well tolerated by the patient and neither do they consistently produce effective symptom relief. Therefore,
there is a need to develop and explore alternative approaches for palliation in patients for whom surgical resection
of the primary rectosigmoid tumor is not feasible or appropriate. RF energy is emerging as a safe and effective
technique to ablate solid tumors.4,6,7 However, the utility of RF energy to palliate tumors of the lower
gastrointestinal tract has not been previously explored. Based on our experience of RF in the management of liver
cancer, we have developed Endoblate™, a bipolar RF probe designed to ablate endoluminal lesions via the
endoscope or operating proctoscope.
CONCLUSIONS
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This preliminary study demonstrated that endoscopic application of bipolar RF ablative technology with
Endoblate™ may hold promise for palliation of patients with widely metastatic or unresectable symptomatic rectal
cancer. Based on our findings, we recommend that further and larger studies, including controlled trials, are
performed to compare this technology with other palliative techniques.
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KEY WORDS: Radiofrequency ablation; Rectosigmoid; Cancer; Endoluminal
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