Proximal early gastric cancer can choose radical total gastrectomy or proximal gastrectomy. The patients have poor nutritional status and quality of life after total gastrectomy. Compare to total gastrectomy, the nutritional status can improve after proximal gastrectomy . But if use simple esophagogastric anastomosis for proximal gastrectomy, the incidence of postoperative reflux esophagitis is high, which seriously affects the quality of life, and the short-term outcome is poorer than the total gastrectomy. If the incidence of postoperative reflux esophagitis can be reduced, proximal gastrectomy would be the treatment choice for proximal early gastric cancer, which may more improve both quality of life and nutritional condition than total gastrectomy.

Double-flap technique is a new surgical reconstruction procedure between esophagus and remnant stomach. It can reduce the occurrence of reflux oesophagitis through reconstruction a simulative cardia. At present, the technique has been carried out in some hospitals in China but still lack large-scale prospective studies and evidence of evidence-based medicine. At present, some retrospective studies have shown that robotic assisted proximal gastrectomy with double-flap technique is safe and effective, and the learning curve is shorter than laparoscopic surgery. The applicant have finished two robotic assisted proximal gastrectomy with double-flap technique cases. Two patients recovered well after surgery, with no occurrence of anastomotic leakage or stenosis and the postoperative quality of life was good. Now we plan to conduct a multi-center, single arm study on proximal early gastric cancer patients(T1N0-1M0 and T2N0M0) to evaluate the feasibility of robotic assisted proximal gastrectomy with double-flap technique , and to evaluate the surgical and oncological safety of this surgical method. Aim to provide initial evidence of evidence-based medicine for its clinical application..

Inclusion Criteria:

1. 20 years ≤ age ≤ 80 years
2. The primary gastric lesions were located in the proximal third of the stomach
3. histologically proven gastric adenocarcinoma (by preoperative gastrofiberscopy)
4. clinical stage IA (T1N0M0) or IB (T1N1M0 / T2N0M0) according to the 8th edition of the American Joint Committee on Cancer System(Clinical stage was determined based on the finding of endoscopic ultrasonography and/or thoraco-abdominal contrast-enhanced computed tomography)
5. scheduled for robotic assisted proximal gastrectomy with D1+/D2 lymphadenectomy, and possible for R0 surgery by this procedures (Lymphadenectomy is performed on the basis of the criteria of the Japanese Gastric Cancer Treatment Guidelines 2021 (6th edition).).
6. The preoperative American Society of Anesthesiologists (ASA) physical status was I-III;
7. The patient's cardiopulmonary function can tolerate robotic assisted surgery;
8. The subjects have signed the informed consent form.

Exclusion Criteria:

1. history of upper abdominal surgery and not suitable for robotic assisted surgery
2. the tumor invades the esophagus 3cm above gastro-esophageal junction (Z-line)
3. with other malignant diseases or have suffered from other malignant diseases within 5 years
4. Excessive tension for esophagogastric anastomosis and require changing the reconstruction procedure
5. women are pregnant or in lactation period
6. Suffering from serious mental illness
7. history of continuous systemic corticosteroid or immunosuppressive drug treatment within 1 month

The data sets generated and/or analysed during the current study are not publicly available due to governmental policy regarding individual information. However, they are available from the Sun Yat-Sen Memorial Hospital data center upon reasonable request, subject to approval by the Sun Yat-Sen Memorial Hospital Ethics Committee and the Data and Safety Monitoring Committee. This will be after the publication of the main findings, in line with standard data-sharing practices for clinical trial data sets. The Sun Yat-Sen Memorial Hospital data center will ensure the confidentiality of all participants' data and will not disclose information by which participants may be identified to any third party other than those directly involved in the treatment of the participant and organisations for which the participant has provided explicit consent for data transfer.