Partially Covered versus Uncovered Self-expandable Metal Stents in the Palliative Treatment of Malignant Distal Biliary Obstruction

Abstract

Introduction: Self-expandable metal stents (SEMSs) are commonly used to relieve malignant biliary obstruction. Covered self-expandable metal stents (CSEMSs) were introduced to improve the patency of SEMSs by preventing tissue ingrowth. Unlike uncovered self-expandable metal stents (USEMSs), which are integrated into the tumor or duct wall, CSEMSs do not embed, but have an increased risk of migration. Although several retrospective studies comparing these two types of stents for malignant biliary obstruction have shown longer patency with CSEMSs, prospective, randomized trials have not been able to confirm these results. Partially covered self-expandable metal stents (PCSEMSs) has been introduced to reduce migration with advantage of CSEMSs preventing tumor ingrowth. The aim of this study was to compare stent patency and clinical outcomes between PCSEMSs and USEMSs in malignant biliary obstruction. Methods: A total of 36 patients with malignant biliary obstruction were randomly assigned to either PCSEMSs (n=16) or USEMSs (n=20) for palliation of biliary obstruction. Duration of stent patency, procedure-related adverse events and intervention for stent occlusion were evaluated. Results: The mean period of follow-up was 105.3±100.8 days for the PCSEMSs group and 180.8±123.3 days for the USEMSs group (P=0.056). Stent occlusion occurred in only 1 patient after 84 days in the PCSEMSs group and in 6 patients after a mean of 146 days in the USEMSs group (P=0.104). Cumulative stent patency estimated by the Kaplan-Meier method showed no significant difference between PCSEMSs group and USEMSs group (P=0.20). There was no procedure-related adverse event in both groups. Additionally, there was no migration of stent in the CSEMSs group. Conclusion: There was no significant difference in stent patency time between PCSEMSs and USEMSs in the palliative treatment of malignant distal biliary obstruction, although there was trend that more stent occlusion occurred in USEMSs group than PCSEMSs group. There was no migration of stent in the CSEMSs group. Further studies with large population are warranted to validate these results.