The incidence of proximal gastric cancer has increased significantly in recent years. This may be due to weight gain, alcohol consumption, gastroesophageal reflux disease (GERD), and precancerous lesions. With a deeper understanding of the pattern of lymph node metastasis and the emergence of anti-reflux procedures, proximal gastrectomy has gradually received clinical attention. For early-stage upper gastric cancer and esophagogastric combination cancer cases that are expected to have a good prognosis, the ideal surgical procedure should be to preserve the distal stomach to improve the quality of life and to choose a reasonable digestive tract reconstruction method to prevent reflux. The anti-reflux effect of various proximal gastrectomy digestive tract reconstruction methods and the advantages and disadvantages of various surgical procedures are controversial, and the recognized ideal reconstruction method has not yet been established. Therefore, we propose a reconstruction called the "C" Single Flap Plasty Reconstruction. This study aimed to investigate the efficacy and safety of proximal gastrectomy combined with "C" Single Flap Plasty Reconstruction in the treatment of gastric cancer.

Inclusion Criteria:

1. Age between 18-80 years old, male or female;
2. 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) according to the eighth edition of the AJCC ;
3. No distant metastasis was observed on preoperative chest radiograph, abdominal ultrasound, or upper abdominal CT;
4. ASA grade 1-3;
5. Patients without contraindications to surgery;
6. Patients and their families voluntarily signed the informed consent form and participated in the study;

Exclusion Criteria:

1. Patients diagnosed with primary tumors or distant metastasis;
2. Patients whose tumor is located in the greater curvature side of the stomach;
3. Patients with coagulation dysfunction that could not be corrected;
4. Patients who were diagnosed with viral hepatitis and cirrhosis;
5. Patients who were diagnosed with diabetes mellitus, uncontrolled or controlled with insulin;
6. Patients with organ failure such as heart, lung, liver, brain, and kidney failure;
7. Patients with ascites or cachexia preoperatively in poor general conditions;
8. Patients diagnosed with immunodeficiency, immunosuppression, or autoimmune diseases (such as allogeneic bone marrow transplant, immunosuppressive drugs, SLE, etc.).
9. Patients refusing to sign the informed consent of the study;