The purpose of this study is to explore the clinical outcomes of the robotic assisted radical gastrectomy for advanced Siewert II/III esophagogastric junction adenocarcinoma（cT2-4a, N-/+, M0）

In recent years, the incidence of gastric cancer has been decreasing year by year in the world, but the incidence of adenocarcinoma of the esophagogastric junction (AEG) has shown a significant upward trend, especially in Western countries such as Europe and the United States. The prognosis of AEG is poor, therefore, it is extremely necessary to establish AEG's best diagnosis and treatment strategies to improve the long-term outcome of AEG. Robotic surgery has been developed with the aim of improving surgical quality and overcoming the limitations of conventional laparoscopy in the performance of complex mini-invasive procedures. The study is designed to explore the clinical outcomes of the robotic assisted radical gastrectomy for advanced Siewert II/III esophagogastric junction adenocarcinoma (cT2-4a, N-/+, M0) by comparing with laparoscopic assisted.

Inclusion Criteria:

• Age from over 18 to under 75 years
• Primary gastric adenocarcinoma (papillary, tubular, mucinous, signet ring cell, or poorly differentiated) confirmed pathologically by endoscopic biopsy
• cT2-4a(clinical stage tumor), N-/+, M0 at preoperative evaluation according to the American Joint Committee on Cancer (AJCC) Cancer Staging Manual 8th Edition
• Expected to perform total gastrectomy with D2+No.19+No.20 lymph node dissction to obtain R0 resection sugicall results.
• Performance status of 0 or 1 on ECOG (Eastern Cooperative Oncology Group) scale
• ASA (American Society of Anesthesiology) class I to III
• Written informed consent

Exclusion Criteria:

• Women during pregnancy or breast-feeding
• Severe mental disorder
• History of previous upper abdominal surgery (except laparoscopic cholecystectomy)
• History of previous gastric surgery (except ESD/EMR (Endoscopic Submucosal Dissection/Endoscopic Mucosal Resection )for gastric cancer)
• Gastric multiple primary carcinoma
• Enlarged or bulky regional lymph node （diameter over 3cm）supported by preoperative imaging
• History of other malignant disease within the past 5 years
• History of previous neoadjuvant chemotherapy or radiotherapy
• History of unstable angina or myocardial infarction within the past 6 months
• History of cerebrovascular accident within the past 6 months
• History of continuous systematic administration of corticosteroids within 1 month
• Requirement of simultaneous surgery for other disease
• Emergency surgery due to complication (bleeding, obstruction or perforation) caused by gastric cancer
• FEV1<50% of the predicted values