Protocol for Comparing the Efficacy of Three Reconstruction Methods of the Digestive Tract After Proximal Gastrectomy

Inclusion Criteria: * Age between 20-75 years old, male or female; * Pathological diagnosis of preoperative endoscopic biopsy: the tumor is located in the upper 1/3 of the stomach (including the esophagogastric junction), and the clinical staging of gastric cancer： Ia and Ib (T1N0M0, T1N1M0, and T2N0M0) (14) according to the eighth edition of the AJCC (15); * No distant metastasis observed on preoperative chest radiograph, abdominal ultrasound or upper abdominal CT; * ASA grade 1-3; * Patients without contraindications to surgery; * Patients and their families voluntarily signing the informed consent form and participating in the study; Exclusion Criteria: * Patients diagnosed with primary tumors or distant metastasis; * Patients whose tumor is located in the greater curvature side of the stomach; * Patients with coagulation dysfunction which could not be corrected; * Patients who were diagnosed with viral hepatitis and cirrhosis; * Patients who were diagnosed with diabetes mellitus, uncontrolled or controlled with insulin; * Patients with organ failure such as heart, lung, liver, brain, kidney failure; * Patients with ascites or cachexia preoperatively in poor general conditions; * Patients diagnosed with immunodeficiency, immunosuppression or autoimmune diseases (such as allogeneic bone marrow transplant, immunosuppressive drugs, SLE, etc.). * Patients refusing to sign the informed consent of the study;