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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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 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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