Biliopancreatic malignancies such as cholangiocarcinoma (CCA) has notoriously been diagnosed late. As such most therapy have been palliative in nature. Cholangioscopy allows for an earlier diagnosis to be made. Brachytherapy with the insertion of catheter with iridium-132 seeds, percutaneously or through endoscopic retrograde cholangiopancreatography (ERCP) was the earliest ablative techniques used. It has been shown to have a beneficial effect only in prolonging survival. Photodynamic therapy (PDT) has also been used for several years. stenting with PDT versus stenting alone for unresectable CCA showed a marked survival benefit with the addition of PDT. However the most exciting endoscopic ablative modality appears to be intraductal radiofrequency ablation using the Habib catheter and device. Several case series have shown the effectiveness of this technique in ablating tumors. This technique is evolving and coupled with early diagnosis of CCA through cholangioscopy will allow for a curative therapy. The crux to the effective treatment of early cancerous lesions in the bile or pancreatic duct is the early diagnosis of such lesions. Effective endoscopic ablative therapy is now available with the advent of radiofrequency ablation probes that can be passed through the duodenoscope via ERCP.
Biliopancreatic malignant neoplasia is an evolving area of interest particularly in terms of treatment since it carries a high association to morbidity and mortality. These types of neoplasia include ampullary adenocarcinoma, cholangiocarcinoma, gallbladder polyp, gallbladder cancer and pancreatic malignancies, of which pancreatic adenocarcinoma being the most common.
When different ablative techniques introduced into the field of gastroenterology, various diseases were addressed. These techniques can be performed directly (e.g., brachytherapy and radiofrequency ablation) or indirectly (e.g., photodynamic therapy). The route of administration is done either endoscopically or by percutaneous transhepatic cholangiography. However, such modalities are frequently employed on advanced disease stage mainly on biliopancreatic malignancies. The aim of this treatment is to ensure palliation of cholestasis or improve duration of survival and quality of life. Its use on early cancerous lesion, on the other hand however, may potentially be curative in nature. However its use remains limited due to limited evidence and further trials are recommended.
Intraluminal brachytherapy (ILBT) in biliopancreatic malignancies is one of the ablative therapies that can be performed either endoscopically or percutaneously. This modality involves the application of iridium-192 isotope seeds mounted on a catheter that are positioned directly across the area of malignant stricture in the biliary system. A variety of radiation dose between 10.4 and 20 Gy is then administered. A central feature of this therapy is that irradiation affects only the localized area around the radiation source. Hence, this technique exerts a local control of tumor by preventing tumor growth or advancement into biliary tree. This also delays the fatal complications from progressive obstructive jaundice. It can be used in conjunction with external beam radiotherapy (EBRT). The principle behind this dual system is that close proximity of the radiation source to the tumor allows administration of higher doses of radiation than what it can be achieved with EBRT alone without damaging surrounding organs.
The evaluation of ILBT had yielded mixed results. One of the earliest endoscopic ablative therapy that utilized brachytherapy in biliopancreatic carcinoma with the insertion of catheter with iridium-192 seeds implanted either percutaneously or through endoscopic retrograde cholangiopancreatography (ERCP) as described by Montemaggi et al.
Photodynamic therapy (PDT) has been used also for several years. It is becoming one of the emerging modalities in treating CCA in patients that present with unresectable tumor. The underlying principle of PDT involves the intravenous administration of a photosensitizer which is known to accumulate preferentially in neoplastic cells, then followed by exposure of the target tissue to a light of appropriate photoactivating wavelength. This mechanism in turn commence a cascade of events by photochemical reaction to generate cytotoxic reactive oxygen species resulting in ischemia, apoptosis and necrosis of tumor cells.
Several studies showed favorable outcomes with the utility of this modality. Among them, the first randomized prospective controlled trial published by Ortner et al.
Endobiliary radiofrequency ablation (RFA) seems to be the most exciting endoscopic ablative modality using the Habib catheter and device.
The technical feasibility, cholangioscopic video recording and fluoroscopic images of the procedure were described in a concise manner in a pilot study conducted by Monga et al.
In the group with hemobilia reported by Tal et al.,
In the group with liver infarction, thermal injury to surrounding vessel was postulated to be the cause of liver infarction. However, the patient survived with conservative management. Liver infarction following endobiliary RFA is rare but calls for more careful pre-interventional imaging to analyze the surrounding tissue, especially vascular and biliary structures prior to RFA procedure.
Several case series have shown the effectiveness of this technique in ablating tumors from the intraluminal ductal aspect. In a retrospective study by Dolak et al.,
High-intensity intraductal ultrasound is a novel application of high-intensity ultrasound used to allow the ultrasound waves to deeply penetrate surrounding tissue and produce localized ablation of tumor cells. It is performed by passing an ultrasound probe over a guidewire into the bile duct during ERCP. Results of some studies show promising outcome in biliary tract malignancy in terms of reduction in the length of the stricture, reduction in tumor size determined by endoscopic ultrasound and the absence of malignant cells or high-grade dysplasia on cytologic specimens.
The crux to the effective treatment of early cancerous lesions in the bile or pancreatic ducts is the early diagnosis of such lesions which has erstwhile not been possible. Most of the studies presented in this review dealt on the advantages of ablative therapies, but predominantly on its use for inoperable biliopancreatic cancer (
The authors have no financial conflicts of interest.
Preradiofrequency ablation cholangioscopic image of cholangiocarcinoma (courtesy of Dr Nageshwar Reddy; personal collection).
Two-week postradiofrequency ablation cholangioscopic image of cholangiocarcinoma (courtesy of Dr Nageshwar Reddy; personal collection).
Habib EndoHPB catheter is delivered through side-viewing duodenoscope. Adapted from EMcision, Habib EndoHPB catheter, with permission from EMcision.
Summary of Literature Review of Studies Concerning the Technical Details, Outcomes and Complications of Endobiliary Radiofrequency Ablation in Addition to Stenting in Malignant Biliary Obstruction
ERCP, endoscopic retrograde cholangiopancreatography; NA, not available; PTC, percutaneous transhepatic cholangiography; RFA, radiofrequency ablation; SEMS, self-expandable metallic stent.