A Multicenter, Prospective, Randomized, Controlled, Non-inferiority Phase III Trial Comparing Function-Preserving Gastrectomy versus Total Gastrectomy in Patients with Locally Advanced Gastric Cancer Achieving Clinical Response after Neoadjuvant Therapy (RESCUE-GC Trial)

INTERVENTION: Functional preservation group (FPG group):Function‐preserving gastrectomy;Total gastrectomy group (TG group):Total gastrectomy with D2 lymphadenectomy; CONDITION: This study targets patients with locally advanced upper‐ or middle‐third gastric adenocarcinoma who respond to neoadjuvant treatment. Eligible patients have baseline clinical stage cT2–4aN0–3M0 disease according to the 8th edition of the AJCC staging system. Responders are defined as patients with CR or PR according to RECIST version 1.1, or SD with marked tumor regression allowing preservation of PRIMARY OUTCOME: 3‐year disease‐free survival rate; SECONDARY OUTCOME: Surgical safety assessment;Reflu Xesophagitis;Oncological safety outcomes;Overall survival;Nutritional status;Quality of life; INCLUSION CRITERIA: 1. Age range: 18 ‐ 75 years old, gender not restricted, voluntarily participate and sign a written informed consent form; 2. Pathological diagnosis: confirmed by gastroscopy biopsy tissue pathology as gastric adenocarcinoma (Gastric Adenocarcinoma), including: tubular adenocarcinoma, papillary adenocarcinoma, mucinous adenocarcinoma, poorly differentiated adenocarcinoma, signet ring cell carcinoma, etc.; 3. Baseline staging imaging staging (enhanced CT or EUS) is for locally advanced gastric cancer (cT2‐4aN0‐3M0, AJCC 8th edition staging); 4. The tumor is mainly located in the upper or middle part of the stomach. According to the JGCA treatment guidelines, at the initial diagnosis, it is determined that a total gastrectomy is necessary for radical treatment, including the following situations: the upper edge of the tumor involves the cardia or is less than 2 cm from the cardia; diffuse lesions are expected to have a resection range exceeding 2/3 of the gast