Résumé
BACKGROUND/AIMS: Although metalic stents are established therapeutic options for the palliation of malignant biliary obstruction, it remains unclear which stricture or stent related factors affect the stent patency. METHODS: Metallic Wallstents (Microvasive, Boston-Scientific, MA, U.S.A.) were inserted endoscopically in 68 patients (mean age; 70.2+/-8.5, M:F=38:30) with malignant biliary obstruction. Patency rates were prospectively analyzed according to the characteristics of malignant strictures including length, morphologic type and degree of stricture. Furthermore, patient age, initial serum bilirubin level, the length of stent, the adequate expansion time, and the location of the distal stent end were evaluated as possible factors affecting the stent patency. Stent patency was assessed using the survival analysis of the Kaplan-Meier estimation and Cox regression analysis. RESULTS: Median overall stent patency was 231 days and overall rate of stent occlusion was 41.2% (28/68). The causes of stent blockage were tumoral ingrowth in 23 patients (33.8%), distal overgrowth of the cancer in 3 (4.4%), proximal overgrowth in 1 (1.5%) and sludge incrustation in 1 patient (1.5%). No significant differences in metallic stent patency rates according to primary tumor type, length and morphologic type of stricture, and length and location of distal end of the stent were found. Log-rank test and multivariate regression analysis, however, demonstrated that the degree of stricture assessed by cannula or guidewire passage and the adequate expansion time of the stent are independent factors associated with long-term metallic stent patency. CONCLUSIONS: Our study showed that early expansibility of the stent and easy passage of larger-caliber instruments over the stricture were favorable factors for long-term patency of the metallic stent.