The investigators study aims to explore the potential function of extensive intraoperative peritoneal lavage in improving the overall survival and progression-free survival for locally advanced gastric cancer after curative resection.

Hypothesis: Overall survival and progression-free survival of locally advanced gastric cancer are improved by extensive intraoperative peritoneal lavage.

Gastric cancer has been one of the most frequently common cancers and remains the third leading cause of death among malignant tumors all over the world. Surgery has always been considered as the most effective treatment. While significant surgical technique and perioperative management have dramatically improved the survival of patients with advanced gastric cancer, patients with T4 stage or serosal-positive gastric cancer often suffer from recurrence as peritoneal dissemination, and the prognosis of those patients is extremely poor. Despite curatively resected, Peritoneal metastasis is completed by the implantation of peritoneal free cancer cells exfoliated from serosa-invasive tumors. Therefore, things need to be done to eliminate the free exfoliated cancer cells on the peritoneal lining in order to reduce the risk of peritoneal recurrence.

A multi-institutional prospective, randomized trial has been launched by Kuramoto recently. The trail was intended to demonstrate the superiority in overall survival of addition of Extensive Intraoperative peritoneal Lavage (EIPL) to standard treatment in patients with≥T3 carcinoma of stomach. Based on the'limiting dilution theory', after total or distal gastrectomy with D2 lymphadenectomy, the peritoneal cavity is extensively rinsed 10 times with 1 L physiological saline at a time, followed by complete aspiration of the fluid. In total, 10 L saline is to be used. In this study, the EIPL-IPC group had a significantly lower incidence of peritoneal recurrence. Furthermore, the 5-year overall survival rate of the patients in the EIPL-IPC group (43.8%) was significantly better than that of the intraperitoneal chemotherapy (IPC) group (4.6%) and the surgery-alone group (0%). All in all, EIPL is easy to carry out, safe and inexpensive. Therefore, gastrectomy with EIPL will be a new standard treatment of gastric cancer.

To ensure the quality of the study, two interim analyses will be planned at the half and the completion of the study respectively. The Data and Safety Monitoring Committee will independently review the interim analysis and stop the study ahead of schedule if necessary. Furthermore, to improve the study progress and quality, the in-house interim monitoring will be performed.

Inclusion Criteria:

1. Lower age limit of research subjects 18 years old and upper age limit of 80 years old.

2. ECOG score standard (ECOG）performance status of 0 or 1 and expected to survive more than 6 months.

3. Without any other malignancies.

4. Written informed consent from the patient.

5. Histologically proven primary gastric adenocarcinoma.

6. Patients planned for open gastrectomy.

7. Patients who have T3 (subserosal) or T4 (serosal) disease based on Ultrasound gastroscopy and intra-operative inspection with any N staging and M0 gastric cancer.

8. No preoperative neoadjuvant chemotherapy.

9. Length of esophageal invasion≤3cm and no need of thoracotomy for resection.

10. Intraoperative inclusion criteria:

    1. Clinically T3, T4a or T4b.
    2. Clinically H0 and M0. No peritoneal dissemination or Distant metastases.
    3. Possible for R0 surgery.

Exclusion Criteria:

1. Female in pregnancy or lactation.
2. Supraclavicular lymph nodes metastases，pelvis or ovarian implantation，peritoneal dissemination，liver，lung and bone metastases.
3. Massive ascites or cachexia.
4. Patients participating in any other clinical trails currently，or participated in other trails within 1 months.
5. Without a history of stomach or esophageal cancers, including stromal tumor，sarcoma，lymphoma and carcinoid.
6. Suffering from other serious diseases, including cardiovascular, respiratory, kidney, or liver disease, complicated by poorly controlled hypertension, diabetes, mental disorders or diseases.
7. Patients with poor compliance or considered to be poor compliance.