A pilot study of a novel tapered and flared fully covered self-expandable metal stent for unresectable malignant distal biliary obstruction: a multicenter study in Japan

BACKGROUND: This study evaluated the feasibility and clinical outcomes of a novel tapered and flared, fully covered, self-expandable metal stent (TF-FCSEMS) for unresectable malignant distal biliary obstruction (UMDBO). METHODS: This multicenter retrospective study included 40 patients who underwent transpapillary placement of a TF-FCSEMS (10-mm cylindrical body with an 8-mm tapered distal end) for UMDBO between May 2023 and July 2024. The primary outcome was time to recurrent biliary obstruction (TRBO). Secondary outcomes included technical and clinical successes, adverse events (AEs), and overall survival. RESULTS: Technical and clinical success rates were 100% and 98%, respectively. During a median follow-up period of 271 days, recurrent biliary obstruction (RBO) occurred in 10 (26%) of the 39 patients who achieved clinical success. The median TRBO was 539 days (95% confidence interval, 389-not reached), and the non-RBO rates at 3, 6, and 12 months were 94%, 71%, and 61%, respectively. Symptomatic stent migration occurred in 2 patients (5.1%), while asymptomatic migration was observed in 3 (7.7%). Post-endoscopic retrograde cholangiopancreatography pancreatitis occurred in four patients (10%). Non-occlusion cholangitis developed in five (13%) patients, mostly with tumor-related duodenal stenosis. All AEs were managed conservatively or endoscopically. CONCLUSIONS: TF-FCSEMS appears to be a feasible and acceptable treatment option for UMDBO. Further prospective studies are required to confirm these findings.