Covered self-expandable metal stents in benign biliary strictures caused by chronic pancreatitis: a randomized controlled trial of 6 versus 12 months of stenting

BACKGROUND: In chronic pancreatitis (CP), a symptomatic benign biliary stricture (BBS) evolves as an adverse event in 3-30%. Treatment by ERCP with a single plastic biliary stent has been disappointing. Multiple plastic stents are more successful but make the procedure more time consuming than treatment with a fully covered self-expandable metal stent (fcSEMS). The most efficient stenting duration of BBS caused by CP is not known. The aim of this multicenter prospective randomized study was to compare the safety and feasibility of 10 mm diameter fcSEMSs placed for 12 months versus 12 mm diameter fcSEMSs placed for 6 months in the treatment of BBS caused by CP. METHODS: The patients were randomized into two groups: either 10 mm diameter fcSEMS for 12 months or 12 mm diameter fcSEMS for 6 months. After stent removal, the patients were followed up at 6 and 24 months with liver function tests and abdominal ultrasound. RESULTS: A total of 62 consecutive patients undergoing ERCP for the treatment of BBS at six centers were enrolled. Four patients in the 10 mm group and five in the 12 mm group were excluded due to a diagnosis of pancreatic cancer, and two in the 10 mm and four in the 12 mm group were excluded because of death from other causes during the 2-year follow-up. In the 10 mm group, one stent became impacted in the bile duct necessitating hepaticojejunostomy; this patient was also excluded from the final analysis. The final sample size was 24 patients in the 10 mm group and 22 in the 12 mm group. In the 12 mm group, one stent migrated requiring re-stenting. Recurrent strictures occurred in 3 of 24 patients (13%) in the 10 mm group and in 4 of 22 patients (18%) in the 12 mm group (p = 0.694). CONCLUSIONS: Both types of fcSEMS are effective in the treatment of BBS secondary to CP. However, the increased risk of pancreatic cancer in these patients should be taken into consideration.