SP Intravenous Chemotherapy Versus SP by HIPEC in Stage Ⅲ Patients After D2 Gastrectomy

Inclusion Criteria: * 18 ≤ age ≤ 70 years old * Histologically diagnosed as stageⅢ gastric adenocarcinoma，and perform D2 radical gastrectomy，as well as have not received any Anti-tumor therapy：chemotherapy,biological treatment or molecular targeted therapy , etc. * The Eastern Cooperative Oncology Group (ECOG) status ≤ 2 * Having given written informed consent prior to any procedure related to the study * Expected survival time ≥3 months Exclusion Criteria: * History of severe hypersensitivity reactions to the ingredients of S-1 or Cisplatin * Hemoglobin\<90g/L * Inadequate hematopoietic function which is defined as below: * white blood cell (WBC) less than 3,500/mm\^3 * absolute neutrophil count (ANC) less than 1,500/mm\^3 * platelets less than 80,000/mm\^3 * Inadequate hepatic or renal function which is defined as below: * serum bilirubin greater than 2 times the upper limit of normal range * alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than 2.5 times the ULN if no demonstrable liver metastases or greater than 5 times the ULN in the presence of liver metastases * blood creatinine level greater than 1.5 times ULN,Creatinine clearance\<60ml/min * Receiving a concomitant treatment with other fluoropyrimidine drug or flucytosine drug * Women who is pregnant or lactating or fertile women of child-bearing potential unless using a reliable and appropriate contraceptive method throughout the treatment period (Including male) * Psychiatric disorder or symptom that makes participation of the patient difficult * Myocardial infarction, existing serious or unstable angina, and patients with cardiac insufficiency in 6 months * Severe complication(s), e.g., paresis of intestines, ileus, radiographically confirmed interstitial pneumonitis or pulmonary fibrosis, glomerulonephritis ,renal failure, poorly-controlled diabetes * Known DPD deficiency * Participate in other clinical trial before the start of this trial * Patient compliance is bad or researchers believe that patients are not suitable for this treatment * Known to have active hepatitis patients