[Resolution of liver metastases in response to S-1 monotherapy in advanced pancreatic cancer--a case report].

We report a case in a late phase II clinical study investigating the efficacy and safety of the oral fluoropyrimidine anticancer drug S-1. The drug proved effective in a patient with inoperable advanced pancreatic cancer in whom radiation therapy was not indicated. The antitumor effect after 4 courses was rated excellent, with a target site (liver) evaluation of CR and overall evaluation of PR. In particular, two liver metastases, measuring 18.7 x 15.4 mm and 16.2 x 14.6 mm, respectively, both resolved, and S-1 was found to exert a potent antitumor effect against metastases. Assessment of adverse events revealed no grade 3 or 4 adverse reactions, and other adverse events were all mild. Based on the above results, S-1 appeared to be effective against advanced pancreatic cancer and showed excellent tolerability.