Single-port Versus Conventional Laparoscopic Surgery for Radical Proximal Gastric Cancer: A Randomized Controlled Trial

Inclusion Criteria: * Age between 18 and 75 years inclusive. ECOG performance status ≤ 2. Histologically confirmed proximal gastric cancer or Siewert type II adenocarcinoma of the esophagogastric junction. Clinical stage cT1-T3, N0-N+, M0. Tumor maximum diameter ≤ 4 cm and esophageal invasion ≤ 2 cm. Candidates for radical proximal gastrectomy (PG) with feasibility of R0 resection and functional anastomosis. Assessed by a Multidisciplinary Team (MDT) as suitable for PG rather than total gastrectomy, with no requirement for neoadjuvant therapy. Radiographic evidence of localized disease (no distant metastasis to liver, lung, or peritoneum via enhanced CT or MRI). ASA physical status classification ≤ III. Adequate bone marrow, hepatic, renal, cardiac, and pulmonary function. Ability to understand and provide written informed consent. Willingness and ability to comply with the 12-month postoperative follow-up schedule. Exclusion Criteria: * Clinical stage T4 or presence of distant metastasis. Esophageal invasion exceeding 2 cm. History of previous major gastric surgery (e.g., partial or total gastrectomy). Other malignant tumors within the last 5 years. Severe organic diseases that preclude safe anesthesia or surgery (e.g., severe heart failure, pulmonary fibrosis). Requirement for emergency surgery due to active gastric bleeding, perforation, or acute obstruction. Pregnant or lactating women. Serious psychiatric disorders or cognitive impairment that interferes with study compliance. Any other condition that, in the opinion of the investigator, would make the participant unsuitable for the study.