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Plastic vs. Covered-Metal Stents for Malignant Common Bile Duct Obstruction

Expected length of survival should guide selection of stents for palliative therapy.

For endoscopic palliation in patients with malignant common bile duct obstruction, data from randomized studies show that self-expanding metal stents (SEMS) stay patent twice as long as polyethylene (PE) stents. However, a known mechanism of SEMS dysfunction is tumor ingrowth, which might be prevented by use of an available silicone polymer–covered metal version (C-SEMS).

To compare the patency rates of C-SEMS (5-mm bare ends; 10-mm diameter) and PE stents (10 Fr), researchers at a single Swedish hospital randomized 100 patients with unresectable malignant common bile duct strictures to PE stents or C-SEMS. Two patients in the C-SEMS group required repeat endoscopic retrograde cholangiopancreatography within 24 hours to reposition their stents.

Median patency times were 3.6 months in the C-SEMS group and 1.8 months in the PE group (P=0.002). Nine C-SEMS and 22 PE patients developed stent failures during the 10-month follow-up (P=0.009). Stent failure in the C-SEMS group was due to tumor overgrowth in 5, dislocation in 3, and sludge in 1, whereas 20 failures in the PE group were caused by sludge, and 2 were dislocations. Median survival time was 5.3 months and 3.9 months for the C-SEMS and PE groups, respectively (P=0.28). Eight C-SEMS patients and three PE patients remained alive without stent failure after 10 months’ follow-up. Sixty-five percent of the C-SEMS group and 49% of the PE group died before stent failure.

Comment: The short median patency for C-SEMS might be explained in part by the short median survival time in this cohort. As expected, tumor overgrowth, rather than ingrowth, and stent migration appear to be more common with C-SEMS than with SEMS. C-SEMS–induced pancreatitis or cholecystitis was not seen in this study. PE stents are a reasonable option for patients whose survival is expected to be short (e.g., those with metastatic disease), whereas expandable metal stents should be reserved for those who are anticipated to survive longer. Further studies are required to determine which expandable metal stent, C-SEMS or SEMS, is more cost-effective.

— Stuart Sherman, MD

Published in Journal Watch Gastroenterology September 22, 2006

Citation(s):

Soderlund C and Linder S. Covered metal versus plastic stents for malignant common bile duct stenosis: A prospective, randomized, controlled trial. Gastrointest Endosc 2006 Jun; 63:986-95.

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