[A case report of S-1 monotherapy responding to unresectable gallbladder cancer].

A 68-year-old man was found to have a gallbladder cancer. Curative operation was impossible because the gallbladder cancer invaded around the gallbladder in CT on 15th of April, 2008. S-1 monotherapy (120 mg/day) was started. S-1 was given orally twice daily for 4 weeks followed by 2 weeks without a treatment. There was no remarkable side effect. The gallbladder cancer was smaller in CT on 25th of September, 2008, and we confirmed a partial response (PR) in CT on 13th of February, 2009. In a pilot phase II study of S-1 for biliary tract cancer, the overall objective response rate was 35.0%. There was no severe side effect. S-1 is one of the effective drugs for biliary tract cancer.