[Clinical study of S-1 for advanced gastric cancer after reduction surgery]

We investigated the clinical efficacy and safety of S-1 retrospectively for the treatment of 32 patients with advanced gastric cancer after reduction surgery (gastrectomy). S-1 was administered orally twice daily, at a standard dose of 80 mg/m(2) per day for 28 days, followed by a 14-day rest. There were 21 patients having only a single residual metastatic site and 11 with two or more metastatic sites. Major residual metastatic sites were peritoneum in 25 patients, lymph nodes in 7, liver in 4 and lung in 2. The response rate by target organ was 28.6% for lymph node metastasis, and 0% for liver and lung metastasis. Peritoneal metastasis was not considered measurable site. The median survival time (MST) after S-1 administration was 573 days (95% confidence interval, 439 to 707 days). The 1-, 2- and 3-year survival rates were 62.3%, 40.3% and 28.2%, respectively. Of the 32 patients, 14 received S-1 for more than a year, and the MST in these patients was 897 days (95% confidence interval, 255 to 1,539 days). The incidence of adverse events was 90.6%, but the incidence of grade 3 or 4 was 12.5%. Long-term administration of S-1 may serve to prolong the survival period of patients with gastric cancer after reduction surgery, particularly in peritoneal metastasis.