Inclusion Criteria:

・ Eligibility criteria

1. Histological diagnosis of gastric adenocarcinoma.

2. Measurable or assessable lesions.

3. Age: 18 ~ 75 years.

4. Performance Status (ECOG): 0 ~ 2.

5. No prior chemotherapy or only one regimen of previous chemotherapy (with a washout
period >4 weeks after the final day of the previous therapy). Adjuvant chemotherapy
is not defined as previous therapy.

6. No history of treatment with CPT-11 or S-1.

7. No history of radiotherapy to the abdomen.

8. Oral intake of S-1 is possible.

9. Adequate function of major organs (bone marrow, heart, lungs, liver etc.). WBC
3,500/mm3 and 12,000/mm3. Hb 10.0 g/dl. Platelet count 100,000/mm3. GOT and GPT
2.5times the upper limit of normal (excluding liver metastasis). T-Bil 2.0mg/dl.
Creatinine <1.5 mg/dl (but if it is 1.0 ~ 1.5 mg/dl, the dose of S-1 can be
decreased according to the dose reduction criteria to allow registration in the
trial). Normal ECG (not considering clinically unimportant arrhythmias and ischemic
changes). (10) Predicted survival for >3 months.

(11) Able to give written informed consent

Exclusion Criteria:

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