Not enough cases enrolled in the study.

Gastric cancer with positive is defined as stage IV disease in 7th AJCC/UICC TNM staging system. Controversy exists on the treatment of this part of patients. This trial aimed to explore the optimal treatment strategy for stage IV gastric cancer with positive peritoneal cytology as the only non-curable factor.

In the 7th AJCC/UICC TNM staging system, gastric cancer with positive peritoneal cytology (CY+) is defined as stage IV disease. In NCCN clinical practice guidelines, it is suggested that positive peritoneal cytology in the absence of visible peritoneal implants should be considered as M1 disease and surgery as initial treatment is not recommended for patients with positive peritoneal cytology. However, in the Japanese gastric cancer treatment guidelines 2014, it is suggested that standard gastrectomy can be proposed for patients with no other non-curative factors and if the CY+ status was revealed after surgery, postoperative treatment with S-1 can be recommended as the tentative standard. Previous studies have also proved that extensive intraperitoneal lavage(EIPL) and Hyperthermic Intraperitoneal Chemotherapy(HIPEC) are effective methods for the treatment of peritoneal metastasis.

In order to optimize the treatment strategy of this part of patients, this trial is designed to compare the effectiveness of 2 treatment strategies.

Inclusion Criteria:

• Pathologically diagnosed gastric adenocarcinoma with endoscopic biopsy;
• Pretreatment clinical stage with computed tomography and/or endoscopic ultrasonography;
• Clinical stage cT2-4 N0-3 M0;
• Standard gastrectomy with D2 lymphadenectomy is needed according to the clinicians' evaluation;
• ECOG performance score ≤2, with tolerance of standard gastrectomy and D2 lymphadenectomy;
• Positive peritoneal cytology;
• Signed informed consent.

Exclusion Criteria:

• Remnant gastric cancer, recurrence gastric cancer or multi-primary cancers;
• Intraoperative identified other unresectable factors including other metastasis except positive peritoneal cytology;
• Postoperative pathologically diagnosed as non adenocarcinoma;
• Pregnant or lactate women;
• Child-bearing period adults who refuse to birth control during the trial;
• Uncontrolled epilepsy, CNS disease or mental disorder that may influence the compliance of the patient;
• Severe/active heart disease, including but not limited to acute coronary syndrome, congestive heart failure with less than NYHA II cardiac function, severe arrhythmia that needs drug control, cardiac infarction within 12 month;
• Organ transplantation patients who needs immune suppression therapy;
• Patients who needs emergency surgery because of bleeding, perforation or obstruction.