This controlled study is designed to evaluate the efficacy of TS-1 on survival compared with surgery alone. Patients will be randomly assigned to receive either surgery alone or surgery followed by treatment with TS-1 within 45 days after curative resection (curability A or B). To assess the efficacy, data on recurrence and survival will be collected from the time of enrollment until 5 years after surgery. To evaluate safety, data on adverse events will be collected from the time of enrollment until 1 year after surgery.

Inclusion Criteria:

• Age 20 to 80
• Hematopoietic WBC ≥ 4,000/mm^3 Platelet ≥ 100,000/mm^3
• Hepatic AST and ALT ≤ 2.5 times upper limit of normal(ULN) Total bilirubin ≤ 1.5 mg/dL
• Renal Creatinine ≤ULN

Exclusion Criteria:

• Prior anticancer treatment