This study aimed to verify the survival benefit of TS-1 plus CDDP combination chemotherapy compared with the monotherapy by TS-1 alone.

This is a randomized, controlled, open-label, parallel, multicenter study. Patients are stratified according to 3 factors ; performance status (ECOG scale: 0, 1, 2), disease stage (unresectable gastric cancer or recurrent gastric cancer (received prior adjuvant chemotherapy or not)) and participating center. Patients are randomized to one of two treatment arms. Arm A: Patients receive oral TS-1 twice daily on days 1-28 followed by 14 days rest. Treatment is repeated every 42 days for up to 4 courses. Arm B: Patients receive CDDP iv on day 8 and oral TS-1 twice daily on days 1-21 followed by 14 days rest. Treatment is repeated every 35 days for up to 5 courses. Patients are followed every 6 months for up to 2 years from the day they participates in this study.

Inclusion Criteria:

• Histologically confirmed adenocarcinoma
• Unresectable and recurrent gastric cancer
• Age 20 to 74
• Performance status 0, 1, or 2 (ECOG)
• Life expectancy 3 months
• No prior chemotherapy or radiotherapy for gastric cancer
• Able to take oral medication
• Evaluable or not evaluable lesion had already checked more than 28 days before participated in this study
• Hematopoietic Absolute granulocyte count lower limit of normal-12,000/mm^3 Platelet ≥ 100,000/mm^3 Hemoglobin ≥ 8.0 g/dL
• Hepatic AST and ALT ≤ 100 U/L ALP ≤ 2 times upper limit of normal (ULN) Bilirubin ≤ 1.5 mg/dL
• Renal Plasma creatinine ≤ ULN Creatinine clearance ≥ 50 mL/min

Exclusion Criteria:

• Pregnant or nursing
• Bleeding from gastrointestinal tract or no diarrhea
• Hypersensitivity to TS-1 or CDDP
• Psychiatric disorder that would preclude study compliance or giving informed consent
• Severe acute or chronic medical or psychiatric condition or laboratory abnormality
• Serious illness or medical condition
• Brain metastasis
• Ascites requiring drainage