Covered Versus Uncovered Self-conformable Metal Stent for Palliation of Primary Malignant Extra-hepatic Biliary Strictures: a Randomized Multicenter Study

Cancer of the pancreas, gallbladder, or bile ducts is the most common cause of malignant obstruction of the biliary tree. Patients who have unresectable tumors have a dismal prognosis in terms of survival and quality of life. In these cases 5-year survival is less than 2% and palliation, such as the establishment of a biliary drainage, is the only treatment available. Two types of stents are routinely used: plastic stents (PS) and self-expandable metal stents (SEMS). The first generation SEMS are uncovered and recurrent obstruction, most frequently caused by tumor ingrowth through the metal mesh, is seen in 16-46%. Recently, covered SEMS have been introduced to prevent tumor ingrowth. Covered SEMS are associated with stent occlusion in 14% of patients. As can be expected, the most frequent cause of stent obstruction in these patients is sludge formation. Stent migration, and cholecystitis and pancreatitis caused by obstruction of the cystic duct and pancreatic duct, respectively, have been suggested to occur more frequently with covered SEMS. To date, however, one randomized trial and three comparative studies compared covered with uncovered SEMS, have found only a non statistically significant trend towards more frequent occurrence of these complications.

From these initial studies comparing uncovered to covered SEMS, it suggested that stent patency may be longer with covered SEMS. However, supporting evidence for the superior efficacy of covered SEMS is lacking. In addition, the issue of safety of covered SEMS, as well as the real world effectiveness of the self conformable SEMS, warrant further investigation.

In this study, the Investigators will include patients with symptoms (jaundice, cholangitis) due to malignant extrahepatic biliary tree obstruction (pancreatic cancer, cholangiocarcinoma, gallbladder cancer, or metastatic lymphadenopathy) who are not candidates for surgical cure either because the tumor is inoperable or because of the patient's poor medical condition due to comorbidities and/or advanced age.

Patients with extrahepatic malignancy in whom a diagnostic work up is still ongoing to establish the possibility of performing a curative approach will not be immediately enrolled. Patients who have been previously treated with a plastic stent will be eligible if the plastic stent was placed within the 4 weeks prior to enrolment in this study.

The purpose of this study is to compare the duration of stent patency of a covered vs. an uncovered biliary self-expandable metal stents (SEMS) placed to relieve biliary obstruction in patients with inoperable extrahepatic malignant biliary obstruction.