A Randomized, Controlled, Open-Label, Multi-center Clinical Study Comparing the Efficacy of Close Follow-Up Versus Adjuvant Chemotherapy in Patients With Stage IB-IIA Gastric or Gastroesophageal Junction Adenocarcinoma Following Radical Surgery

Inclusion Criteria: * 1.Aged ≥18 years of either gender. 2.Histologically confirmed adenocarcinoma of the stomach or gastroesophageal junction with an ECOG performance status score ≤2. 3.Pathologic TNM stage IB-IIA gastric or gastroesophageal junction adenocarcinoma, excluding T2N1. 4.Curative surgical resection of the primary tumor completed. 5.Laboratory test criteria as below: 1. Absolute neutrophil count (ANC) ≥1.5×10⁹/L without granulocyte colony-stimulating factor administration within the preceding 14 days; 2. Platelet count ≥100×10⁹/L without blood transfusion within the preceding 14 days; 3. Hemoglobin \>9 g/dL without blood transfusion or erythropoietin administration within the preceding 14 days; 4. Total bilirubin ≤1.5×upper limit of normal (ULN); 5. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5×ULN; 6. Serum creatinine ≤1.5×ULN and calculated creatinine clearance (Cockcroft-Gault formula) ≥60 mL/min; 7. Adequate coagulation function: international normalized ratio (INR) or prothrombin time (PT) ≤1.5×ULN; 8. Cardiac biomarkers within normal range; isolated laboratory abnormalities deemed clinically insignificant by the investigator are acceptable. 6.Voluntary participation and written informed consent obtained prior to study enrollment Exclusion Criteria: * 1\. Other malignant tumors of the stomach. 2. Receipt of any anti-tumor therapy other than the chemotherapy specified in this protocol prior to screening or planned administration of such therapy during the trial (including radiotherapy, targeted therapy, immunotherapy, etc.). 3\. Concurrent or prior malignancy at other anatomic sites, except for adequately treated carcinoma in situ of cervix, basal cell carcinoma of skin, or other malignancies surgically cured with no disease recurrence for at least 5 years. 4\. Presence of any severe or uncontrolled systemic diseases as follows: 1. Unstable angina, congestive heart failure, or chronic heart failure classified as NYHA Grade ≥Ⅱ. 2. Resting electrocardiogram showing severe, symptomatic and refractory abnormalities in cardiac rhythm, conduction or morphology, including complete left bundle branch block, second-degree or higher atrioventricular block, ventricular arrhythmia or atrial fibrillation. 3. History of arterial thrombosis, embolism or ischemic events within 6 months before enrollment, such as myocardial infarction, unstable angina, cerebrovascular accident or transient ischemic attack. 4. Poorly controlled hypertension (systolic BP\>140 mmHg, diastolic BP\>90 mmHg). 5. History of non-infectious pneumonia requiring glucocorticoid treatment within 1 year prior to first study drug administration, or clinically active interstitial lung disease at screening. 6. Active pulmonary tuberculosis. 7. Active or uncontrolled infection requiring systemic treatment. 8. Clinically active diverticulitis, intra-abdominal abscess or gastrointestinal obstruction. 9. Hepatic diseases including liver cirrhosis, decompensated liver disease, acute or chronic active hepatitis. 10. Poorly controlled diabetes mellitus (fasting blood glucose, FBG\>10 mmol/L). 11. Urinalysis showing ≥2+ proteinuria confirmed by 24-hour urinary protein quantification\>1.0 g. 12. Psychiatric disorders rendering the subject unable to comply with study treatment. 5\. Current participation in another clinical trial or participation in any other clinical trial within the preceding 3 months. 6\. Known hypersensitivity to any investigational drugs used in this study. 7. Subjects deemed ineligible for enrollment at the Investigator's discretion.