The purpose of this study is to determine whether S-1 and oxaliplatin as neoadjuvant chemotherapy may improve survival benefit compared with control.

Inclusion Criteria:

1. DISEASE CHARACTERISTICS:

   Histologically confirmed gastric adenocarcinoma Locally advanced disease:Clinical stage T3-4, N0-3, M0 (according to the Japanese gastric cancer classification)

2. Planning to undergo gastric cancer D2 surgery after neoadjuvant chemotherapy

3. Age:20 to 75

4. Performance status:ECOG 0-2

5. Life expectancy:Not specified

6. Hematopoietic:WBC 4,000-12,000/mm^3；Granulocyte count ≥ 2,000/mm^3；Platelet count ≥ 100,000/mm^3；Hemoglobin ≥ 9.0 g/dL;Hepatic:AST and ALT ≤ 100 U/L；Bilirubin ≤ 1.5 mg/dL

7. Adequate organ function

8. Able to swallow oral medication

9. Written informed consent

Exclusion Criteria:

1. Synchronous or metachronous (within 5 years) malignancy other than carcinoma in situ
2. Pregnant or breast-feeding women
3. Severe mental disease
4. Systemic administration of corticosteroids, flucytosine, phenytoin or warfarin
5. Other severe complications such as paralytic ileus, intestinal pneumonitis, pulmonary fibrosis, or ischemic heart disease
6. Myocardial infarction within six disease-free months