Introduction
Self-expanding metal stents (SEMS) are recommended by guidelines to relieve biliary obstruction caused by malignant strictures in a palliative setting. There are three types of SEMS, uncovered (UC), semi-covered (SC), and fully covered (FC) indicating the degree to which they are covered by a plastic film. The main concerns regarding bile duct stents are their ability to provide adequate drainage, maintain long-term patency, and overall safety. The intention with the plastic covering is to prevent tumour ingrowth and occlusion of the stent. However, this also makes the stents more liable to dislodge spontaneously (1). There are conflicting reports on UC and SC stents regarding long-term patency; some studies have shown a higher frequency of dysfunction in UC stents while others have not (2, 3). Only a few studies have examined the use of FC stents(4). The aim of this study is to examine the differences in long-term patency of UC, SC, and FC SEMS in palliative patients with jaundice caused by malignant obstruction of the distal bile duct.
Aims & Methods
In this prospective randomized multicenter study patients were recruited between March 2020 and August 2024 at 13 centers in Sweden performing ERCPs. Patients with malignant extrahepatic strictures, where curative surgery was considered unlikely, were included. Patients were randomized in a 1:1:1 ratio to receive UC, SC, or FC SEMS and followed sequentially for 12 months. The primary outcome was stent failure defined as either the patient undergoing re-ERCP or other biliary drainage intervention or clinical and laboratory signs indicating stent dysfunction. Patients were censored at stent failure, death, time point of curative surgery or when the follow-up time ended. This study was registered at ClinicalTrials.gov (NCT06453590).
Results
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A total of 450 patients who had reached their respective endpoints were included in this preliminary intention-to-treat analysis: 163 patients in the UC group, 151 in the FC group and 136 in the SC group. The majority (83%) of the patients had pancreatic cancer. After 12 months of follow-up, 50 patients (11%) were alive with a functioning stent, 151 patients (34%) had received palliative oncological treatment, and 18 patients (4%) had undergone surgery with curative intent. Stent failure occurred in 17% (95% CI: 11-23%) of the UC group, 13% (95% CI: 7-18%) of the FC group, and 7% (95% CI: 3-12%) of the SC group. The failure rate was lower in the SC group (HR 0.4; 95% CI: 0.2-0.8) compared to the UC group. There was a non-significant difference in failure rate in the FC group (HR 0.7; 95% CI: 0.4-1.3) relative to the UC group.
Conclusion
To our knowledge, this is the first prospective randomized trial comparing the long-term patency of the three different types of SEMS. The results suggest that semi-covered SEMS have the lowest rate of stent failure in patients with extrahepatic malignant obstruction and may therefore be the most appropriate choice of stent for palliative patients.
References
1. Kim HS, Lee DK, Kim HG, Park JJ, Park SH, Kim JH, et al. Features of malignant biliary obstruction affecting the patency of metallic stents: a multicenter study. Gastrointest Endosc. 2002;55(3):359-65.
2. Saleem A, Leggett CL, Murad MH, Baron TH. Meta-analysis of randomized trials comparing the patency of covered and uncovered self-expandable metal stents for palliation of distal malignant bile duct obstruction. Gastrointest Endosc. 2011;74(2):321-7.e1-3.
3. Almadi MA, Barkun AN, Martel M. No benefit of covered vs uncovered self-expandable metal stents in patients with malignant distal biliary obstruction: a meta-analysis. Clin Gastroenterol Hepatol. 2013;11(1):27-37.e1.
4. Yamashita Y, Tachikawa A, Shimokawa T, Yamazaki H, Itonaga M, Sakai Y, et al. Covered versus uncovered metal stent for endoscopic drainage of a malignant distal biliary obstruction: Meta-analysis. Dig Endosc. 2022;34(5):938-51.
Disclosure
The study received partial funding from Boston Scientific Nordic AB
