A Randomized Phase II Trial of Neoadjuvant Chemotherapy Compared With Chemoradiotherapy in Gastric Adenocarcinoma

Inclusion Criteria: * Histologically or cytologically proven locally advanced gastric adenocarcinoma in patients staged as cT3-4N0M0 or anyTN+M0 * No distant metastasis in liver,lung,bone,central nervous system(CNS),no peritoneal transplantation * No prior abdominal or pelvic radiotherapy * Karnofsky performance status(KPS)≥ 70, predictive life span no less than 6 months * Patients must have normal organ and marrow function as defined below: Leukocytes: greater than or equal to 3,000 G/L; Platelets: greater than or equal to 100,000/mm3 .Hemoglobin:greater than or equal to 10g/L .Total bilirubin: within normal institutional limits; AST/ALT: less than or equal to 1.5 times the upper limit; Creatinine within normal upper limits * Informed consent Exclusion Criteria: * Any prior chemotherapy or other cancer treatment prior to this protocol * Patients with other cancer history except cervical carcinoma in situ and non-malignant melanoma skin cancer * With any distant metastasis in liver,lung,bone,CNS,or peritoneal transplantation * History of allergic reactions attributed to similar chemical or biologic complex to S-1 or Xeloda or Oxaliplatin * Uncontrolled illness including, but not limited to, active infection, symptomatic heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness * History of myocardial infarction within the past 6 months or history of ventricular arrhythmia * History of prior radiation to the abdomen * Pregnant or lactating females