Evaluating the tissue effects of balloon-based endobiliary radiofrequency ablation in porcine bile ducts

Balloon-assisted laser application for endoscopic treatment of biliary stricture

OBJECTIVES

Malignant biliary stricture is a ductal narrowing of the bile duct that is often diagnosed at an advanced stage, leading to difficulty in resection. The current study aims to evaluate the feasibility of endobiliary laser treatment by quantifying the extent of coagulative necrosis in tissue under various conditions.

METHODS

Ex vivo and in vivo porcine bile tissues were used for endobiliary laser treatment to characterize the dosimetric responses of the tissue to various treatment conditions: power level, irradiation time, and number of treatments. 532 nm laser light was coupled with a balloon-integrated diffusing applicator (BDA) to deliver the laser light endoscopically for tissue coagulation. The coagulated regions (maximum length and depth) in the treated tissues were evaluated histologically for quantitative comparison.

RESULTS

Dosimetric evaluations with ex vivo liver tissue confirmed that both maximum length and depth of coagulative necrosis (CN) increased with applied power and number of treatments. Ex vivo bile duct tests demonstrated that BDA-assisted laser treatment at 10 W for 12 s reproducibly yielded CN with a length of 5.8 ± 1.6 mm and a depth of 0.6 ± 0.2 mm. In vivo tests presented that endoscopic laser treatment using the BDA created CN on the ductal surface without any perforation. Microscopic examinations revealed that a dense inflammatory cell infiltration and eosinophilic area in the in vivo treated tissue. The extent of CN in the in vivo tissue was 40% longer and 120% deeper (length: 8.1 ± 0.7 mm; depth: 1.3 ± 0.2 mm), compared to that in the ex vivo tissue.

CONCLUSION

BDA-assisted laser treatment could be a feasible option for endoscopic treatment of biliary stricture with uniform ablation at the circumference of bile duct. Further in vivo studies will be performed in a large number of stricture-developed porcine models to examine both efficacy and safety of the proposed endobiliary laser treatment for clinical translations.

Endoluminal radiofrequency ablation in patients with malignant biliary obstruction: a randomised trial

BACKGROUND

Endoluminal radiofrequency ablation (RFA) has been promoted as palliative treatment for patients with cholangiocarcinoma (CCA) and pancreatic ductal adenocarcinoma (PDAC) in order to improve biliary drainage and eventually prolong survival. No high level evidence is, however, available on this technique.

DESIGN

In this randomised controlled study, we compared endoluminal RFA plus stenting with stenting alone (control group) in patients with malignant biliary obstruction; metal stents were primarily placed. Primary outcome was overall survival; secondary outcomes were stent patency, quality of life and adverse events. In a superiority design, survival was assumed to be doubled by RFA as compared with 6.4 months in the control group (n=280).

RESULTS

A total of 161 patients (male:female 90:71, mean age 71±9 years) were randomised before recruitment was terminated for futility after an interim analysis. Eighty-five patients had CCA (73 hilar, 12 distal) and 76 had pancreatic cancer. There was no difference in survival in both subgroups: for patients with CCA, median survival was 10.5 months (95% CI 6.7 to 18.3) in the RFA group vs 10.6 months (95% CI 9.0 to 24.8), p=0.58)) in the control group. In the subgroup with pancreatic cancer, median survival was 6.4 months (95% CI 4.3 to 9.7) for the RFA vs 7.7 months (95% CI 5.6 to 11.3), p=0.73) for the control group. No benefit was seen in the RFA group with regard to stent patency (at 12 months 40% vs 36% in CCA and 66% vs 65% in PDAC), and quality of life was unchanged by either treatment and comparable between the groups. Adverse events occurred in seven patients in each groups.

CONCLUSION

A combination of endoluminal RFA and stenting was not superior to stenting alone in prolonging survival or improving stent patency in patients with malignant biliary obstruction.

TRIAL REGISTRATION NUMBER

NCT03166436.

Endoscopic intraductal radiofrequency ablation for extrahepatic cholangiocarcinoma: An update (2023)

Recently, endoscopic intraductal radiofrequency ablation (ID-RFA) has attracted attention as a local treatment method for malignant biliary obstruction (MBO). ID-RFA causes coagulative necrosis of the tumor tissue in the stricture and induces exfoliation. Its effects are expected to extend the patency period of biliary stents and prolong the survival period. Evidence for extrahepatic cholangiocarcinoma (eCCA) is gradually accumulating, and some reports show significant therapeutic effects in eCCA patients without distant metastasis. However, it is still far from an established treatment technique, and many unsolved problems remain. Therefore, when performing ID-RFA in clinical practice, it is necessary to understand and grasp the current evidence well and to operate appropriately for the true benefit of the patients. This paper reviews the current status, issues, and prospects of endoscopic ID-RFA for MBO, especially for eCCA.

Updated evidence on the clinical impact of endoscopic radiofrequency ablation in the treatment of malignant biliary obstruction

Endoscopic biliary radiofrequency ablation (RFA) was recently developed as a novel adjunctive procedure and a promising therapeutic option in patients with malignant biliary obstruction (MBO). RFA can achieve local tumor control, resulting in improved biliary stent patency and a potential survival benefit. However, the efficacy of biliary RFA remains controversial, and previous studies have shown conflicting results. At present, extrahepatic cholangiocarcinoma is considered the condition most effectively treated by biliary RFA, but there is limited research even on this point. Further, limitations of RFA associated with the devices used during the procedure are an important subject of discussion. In addition to further well-designed clinical trials, development of innovative devices is warranted to investigate and conclusively establish the usefulness of biliary RFA. In this review we summarize the updated evidence regarding the use of endoscopic biliary RFA for MBO and discuss issues that should be addressed in future studies.

Feasibility of balloon-based endobiliary radiofrequency ablation under cholangioscopy guidance in a swine model

Although endobiliary radiofrequency ablation (RFA) has demonstrated considerable potential for the treatment of biliary strictures, conventional catheter RFA has several limitations. This study aimed to evaluate the feasibility of a novel cholangioscopy (CS)-guided balloon-based RFA procedure in vivo using a swine model. CS-guided balloon-RFA was performed under endoscopic retrograde cholangiography guidance at target temperatures of 60 ℃ or 70 ℃, which were maintained for 60 s. We evaluated the technical feasibility, adverse events, and histological effects associated with the procedure. Twelve sites were ablated in seven miniature pigs. The CS-guided balloon-RFA procedure was technically successful in all cases without any hindrance. Mucosal changes could be detected during RFA, and the ablation area was identified on CS. Necropsy was performed in four pigs on the same day as the procedure: the tissue samples showed coagulative necrosis, and the entire internal circumference of the bile duct was uniformly ablated. The mean lengths of the ablation area in the samples ablated at 60 °C and 70 °C were 20.64 and 22.18 mm, respectively, while the mean depths were 3.46 and 5.07 mm, respectively. The other three pigs were reared and euthanized and autopsied 35 days after the procedure. The site to be ablated had replaced the granulation tissue and fibrotic changes. No adverse events were observed in any case. CS-guided balloon-RFA appears to be a promising option for treating biliary strictures. This preliminary study could pave the way for the evaluation of this procedure in future human clinical trials.