[Progression of gastric cancer observed for three and a half years under S-1 administration]

A 60-year-old male patient noticed a sudden epigastric pain and visited our hospital for treatment. Active gastric ulcer was discovered by a routine gastrointestinal endoscopy. Moderately differenciated tubular adenocarcinoma was confirmed by biopsy and was advised to take surgical treatment. However, he refused to go on with gastrectomy and selected to take S-1 as an oral anti-tumor drug instead. Despite many approaches to convince the patient to have surgery, three and a half years passed. Macroscopic findings have changed from 0-IIc type to infiltrating advanced type cancer. Finally, we persuaded him to take a surgical resection, but peritoneal dissemination was evident. Using S-1 against gastric cancer is common. However, S-1 should not be used before another evidence-based curative treatment is available. Furthermore, drugs should have been changed to others, if not effective. A rare clinical course is discussed.