OBJECTIVE: Gastric cancer is the most frequent cancer in Japan and is an important cause of growing national Health care costs. However, few studies focusing on the costs of treating gastric cancer in Japan have been conducted. We previously reported the costs of chemotherapy for advanced or recurrent gastric cancer. Our results have shown that the costs of hospitalization and supportive care were cost-drivers in total medical costs during chemotherapy. In this study, we comprehensively investigated medical costs from diagnosis through terminal care in patients with advanced or recurrent gastric cancer. METHODS: Patients with advanced or recurrent gastric cancer who received the newly developed oral fluoropyrimidine TS-1 or conventional intravenous chemotherapy were identified on the basis of ordering system data at Showa University Hospital from January 1998 through July 2001. The costs during diagnosis, chemotherapy, and terminal care were evaluated according to Japanese National Health Insurance fee schedule. RESULTS: Costs were evaluated in 13 patients receiving TS-1 and in 10 patients receiving conventional intravenous chemotherapy. Monthly costs during diagnosis, chemotherapy, and terminal care in the TS-1 group were 597,057 +/- /105,148 (mean +/- SE) Yen, 327,640 +/1 47,647 Yen, and 687,595 +/- / 96,276 Yen. The corresponding costs for conventional intravenous chemotherapy were 615,150 +/1 / 95,299 Yen, 852,874 +/- / 62,412 Yen, and 619,721 +/- / 86,745 Yen. Monthly costs during chemotherapy were significantly lower in the TS-1 group than in the conventional intravenous chemotherapy group, whereas costs during diagnosis and terminal care were similar in the groups. CONCLUSIONS: Medical costs from diagnosis through terminal care are high in patients with advanced or recurrent gastric cancer. The use of oral anticancer drugs such as TS-1, which facilitates transition from inpatient to ambulatory treatment, reduces medical costs in patients with gastric cancer.