[Long-term disease-free survival by S-1 therapy in a case of gastric cancer with peritoneal dissemination].

The patient was a 77-year-old woman who underwent gastrectomy for gastric cancer. Since the patient had positive peritoneal washing cytology and positive peritoneal dissemination, she was started on oral S-1 therapy post-surgery for 4 weeks, followed by a 2-week rest period. During the first course of therapy, her white blood cell count decreased; therefore, the regimen was changed to a 1-week administration, followed by a 1-week rest period. No subsequent adverse events were noted. The patient has experienced no relapse in the four years she has been followed up after surgery in our outpatient clinic. We report our experience with an elderly patient for whom S-1 monotherapy was effective in the treatment of gastric cancer with peritoneal dissemination.