The goal of this clinical trial is to evaluate postoperative adaptive adjuvant therapy in patients with gastric or gastroesophageal junction adenocarcinoma after neoadjuvant chemotherapy plus immunotherapy and radical gastrectomy.The main questions it aims to answer are:
1. In patients with poor pathological response, does switching to a alternative postoperative treatment regimen improve survival? 2. In patients with complete pathological response, can observation without routine postoperative treatment maintain favorable survival outcomes? Participants will be assigned to different cohorts according to their pathological response after surgery and will be followed regularly for recurrence, survival, and treatment-related side effects.
Voluntarily signed written informed consent.
Aged 18 to 75 years, inclusive, regardless of sex.
Underwent radical gastrectomy with D2 or more extended lymphadenectomy and achieved R0 resection. Surgical approaches may include open or laparoscopic surgery.
Histopathologically confirmed gastric or gastroesophageal junction adenocarcinoma.
Presence of liver, peritoneal, or other distant metastases.
Inability to take oral medications.
Unresolved postoperative complications at the time of randomization, such as postoperative infection, anastomotic leakage or wound dehiscence, gastrointestinal bleeding, pancreatic fistula, or intestinal obstruction.
Uncontrolled pericardial effusion, uncontrolled pleural effusion, or clinically significant moderate or greater ascites at screening, defined as any of the following: pleural effusion or ascites with clinical symptoms and detectable by physical examination; or pleural effusion or ascites requiring drainage and/or intracavitary treatment during screening.