Radiofrequency Ablation for Malignant Biliary Obstruction

Introduction

Biliary obstruction is the most relevant life limiting factor in patients suffering from primary or secondary bile duct malignancies. Underlying tumors, such as extrahepatic cholangiocarcinoma (CCa) of Klatskin type, pancreatic adenocarcinoma or metastases of colorectal cancer, are often diagnosed at an advanced stage when presenting with biliary obstruction. This mostly restricts treatment strategies to palliative management. Within this setting the prevention of biliary complications like jaundice, cholangitis or cholangiosepsis is one of the therapeutic key factors to extend survival and maintain quality of life [De Groen, Skipworth]. Endoscopic stenting of the biliary tract is an easy and safe approach to restore biliary drainage [Smith]. Self-expanding metal stents are preferred to plastic stents because of the lower risk of stent occlusion [Kaassis, Soderlund]. In addition to stenting endoscopic therapies that directly affect the local tumor mass, have been developed within the past years. First of all, photodynamic therapy using different photosensitizers has shown promising results for the reduction of tumor size and maintenance of biliary drainage [Ortner, Zoepf]. However, the patient management for this treatment involving peri-interventional photosensitivity remains cumbersome.

Recently, an endoscopically applicable radiofrequency catheter for the biliary tract, the so called HabibTM EndoHBP catheter, was introduced into the market. It uses bipolar electrical energy for tissue coagulation and can be applied without any special patient preparation in the context of an endoscopic retrograde cholangiopancreatography (ERCP) examination. RFA is well known from transcutaneous applications, where it already proved to be effective as a treatment option for hepatocellular carcinoma or intrahepatic CCa [Minami]. The new HabibTM EndoHBP catheter was already evaluated ex vivo [Itoi] and showed promising results concerning safety and prevention of stent occlusion in the context of one small retrospective clinical study [Steel].

Primary objective

Feasibility and safety of endoscopic radiofrequency ablation with the HabibTM EndoHBP catheter for the treatment of malignant biliary obstruction

Study Design

Retrospective analysis of prospectively gained clinical data

Primary endpoint

Technical failures during the RFA procedure

Secondary endpoints

1. Complications during the RFA procedure
2. Hospital stay
3. Adverse events during hospital stay and unil first clinical control after discharge (an expected average of 4 weeks after RFA procedure)
4. 30-day and 90-day mortality

Study Population

All patients who underwent endoscopic radiofrequency ablation with the HabibTM EndoHBP as a treatment for malignant biliary obstruction between November 2010 and December 2012 in Austria.

Methods

Endoscopic examination report databases will be screened for "radiofrequency ablation" in the context of an "endoscopic retrograde cholangiopancreatography" to identify the mentioned study population. Examination reports, discharge letters and patient curves of the study patients will be screened to yield the following parameters:

• Demographics
• Sex
• Age at first RFA-intervention
• Underlying disease that led to malignant biliary obstruction
• Type of underlying disease
• Time from diagnosis to first RFA-intervention
• Previous treatment attempts (chemotherapy, radiation therapy, photodynamic therapy)
• Procedure related parameters
• Prior biliary stents (type, amount)
• Date of RFA procedure
• Amount of RFA-applications during the procedure (energy, time)
• Technical failure of the RFA catheter during the RFA procedure (defined as any technical problem that hinders the satisfactory application of RFA)
• Complications during the RFA procedure (defined as any adverse change from the subject's baseline condition, i.e. any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease which is considered to be clinically relevant by the physician, whether or not considered related to the medical device)
• Stenting after the procedure (type, amount)
• Post-interventional parameters
• Days of hospitalization after the RFA procedure
• Adverse events during hospital stay and until first clinical control after discharge (an expected average of 4 weeks after RFA procedure) defined as any adverse change from the subject's baseline condition, i.e. any unfavorable and unintended sign including an abnormal laboratory finding, symptom or disease which is considered to be clinically relevant by the physician, whether or not considered related to the medical device
• Survial status (dead/alive) at the time of the data collection
• (Cause of death)
• (Time between first RFA procedure and death)

Data processing will be done after pseudonymization using continuous patient identification numbers. All parameters will be assessed descriptively. For scaled parameters (e.g. age) median and range will be calculated, for nominal parameters (e.g. type of underlying disease) the proportions of sub-items will be reported. Mortality will be assessed creating a Kaplan Meyer curve. 30-day and 90-day mortality will be extrapolated from this curve. All data processing will be done with SPSS 19.0.

Risk/Benefit assessment

Due to its retrospective design this study does not inherit any risk for the study patients.

Expected impact and Outlook

The results of this study may help to better understand the feasibility and safety profile of endoscopic radiofrequency ablation with the HabibTM EndoHBP catheter with potential effects on future applications.