[A case of a patient with gastric cancer and peritoneal dissemination who survived for more than 10 years after successful treatment with S-1].

A 50-year-old female patient underwent distal gastrectomy and intraperitoneal CDDP administration for advanced gastric cancer accompanied by severe peritoneal dissemination. She valued her quality of life and chose an oral anticancer drug, S-1, as a postoperative chemotherapy agent. S-1 was administered at a dose of 100mg/body/day for 4 weeks, followed by a 2- week rest.