Long-term results of palliative placement of very low-axial force self-expandable metallic stents for malignant colorectal obstruction.

Objectives: Stent placement is a standard option for palliative decompression in patients with malignant colorectal obstruction. Long-term stent placement is associated with perforation, migration, and stent occlusion. Perforation is associated with life expectancy. Several studies have shown that stents with a high axial force (AF), which is defined as the force required to maintain the stent straight after it has bent, are associated with a higher perforation rate. Therefore, we evaluated the long-term outcomes of using a very low AF stent (Niti-S Enteral Colonic Uncovered stent D-type) for palliative purposes. Methods: Eighty-one consecutive patients with malignant colorectal obstruction in 33 medical institutions were evaluated. A stent with very low AF was placed using an endoscope system. We evaluated the adverse events (including perforation, migration, and stent occlusion), 1-year survival rate, and cumulative patency rate. Univariate analysis was conducted using Fisher's exact test. The overall survival and cumulative patency rates were assessed using the Kaplan-Meier method. Results: The 1-year cumulative survival rate was 37.8% after stent placement. The 3-month, 6-month, and 1-year cumulative patency rates after stenting were 93.6%, 84.2%, and 75.8%, respectively. The major adverse events included stent migration (6.2%), stent occlusion (9.9%), and perforation (2.5%). Chemotherapy was administered in 26 cases (32.1%) after stenting, and bevacizumab was administered in five cases. However, no cases of perforation occurred following bevacizumab administration. Conclusions: Our results suggest that very low AF stents are safe and effective. Therefore, they may be a suitable option for applications, such as palliation. (UMIN 000011304).