Five-Year Follow-Up of the Phase III ASCOT Trial of Adjuvant S-1 After Resection for Biliary Tract Cancer.
Masafumi Ikeda, Kohei Nakachi, Masaru Konishi et al.
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In 30 seconds
This prespecified five-year follow-up of the multicenter, open-label, randomized phase III ASCOT trial assessed adjuvant S-1 versus observation after resection for biliary tract cancer in 440 patients in Japan. At a median follow-up of 61.5 months, five-year overall survival was 64% with S-1 and 52% with observation (HR, 0.72 [95% CI, 0.55 to 0.95]; one-sided P = .01). Median overall survival was 8.2 years and 5.9 years, respectively. The authors report that the survival benefit was sustained and generally consistent across subgroups.
Key findings
- Five-year overall survival was 64% with S-1 versus 52% with observation (HR, 0.72 [95% CI, 0.55 to 0.95]; one-sided P = .01).
- Median overall survival was 8.2 years with S-1 and 5.9 years with observation.
- Median relapse-free survival was 3.5 years with observation versus 6.1 years with S-1; stratified HR was 0.76 (95% CI, 0.59 to 0.98).
- Treatment effects were generally consistent across subgroups.
Why it matters
The extended follow-up indicates that the overall-survival advantage associated with adjuvant S-1 after biliary tract cancer resection persisted beyond the previously reported three-year analysis. These results provide longer-term evidence to inform postoperative treatment discussions, while the trial’s randomized design supports comparison with observation in the studied population.
What to keep in mind
The trial was open-label and conducted in Japan; the abstract does not report outcomes beyond the five-year follow-up analysis.