To compare the incidence of internal hernia, overall survival and short-term surgical safety of routine closure of the surgically created mesenteric defects versus non-closure for patients with adenocarcinoma of the gastric or esophagogastric junction who underwent radical gastrectomy (D1+/D2 lymph node dissection).

Inclusion Criteria:

• Aged 18-75 years；
• Primary lesion is diagnosed with endometrial biopsy as adenocarcinoma of the stomach or esophagogastric junction, including: papillary adenocarcinoma, tubular adenocarcinoma, mucinous adenocarcinoma, poorly cohesive carcinoma (including signet ring cell carcinoma and other variants), mixed adenocarcinoma, etc.；
• The gastric primary lesion is located in the antrum, body or fundus of stomach or the esophagogastric junction. It is expected that radical gastrectomy with D1+/D2 lymph node dissection achieves R0 resection (multiple primary cancers are also applicable)；
• BMI(Body Mass Index) < 30 kg/m2；
• No history of upper abdominal surgery (except for laparoscopic cholecystectomy)；
• No prior treatment of chemotherapy, radiotherapy, targeted therapy, immunotherapy, etc.；
• Preoperative ECOG (Eastern Cooperative Oncology Group) performance status score 0 or 1；
• Preoperative ASA (American Society of Anesthesiologists) scoring I-III；
• Sufficient vital organ functions；
• Signed informed consent.

Exclusion Criteria:

• Women during pregnancy or lactation；
• Suffer from other malignant tumors within 5 years；
• Preoperative body temperature ≥ 38°C or complicated with infectious diseases requiring systemic treatment；
• Severe mental illness；
• Severe respiratory disease；
• Severe liver and kidney dysfunction；
• History of unstable angina or myocardial infarction within 6 months；
• History of cerebral infarction or cerebral hemorrhage within 6 months；
• Continuous application of glucocorticoid within 1 month (except for topical application)；
• Accompanied by gastric cancer complications (bleeding, perforation, obstruction, etc.) ；
• The patient has participated in or is participating in other clinical studies (within 6 months).