Postoperative Adjuvant Therapy for Stage II-III Gastric Cancer

Inclusion criteria

• Patients who have undergone D2 gastrectomy, achieved R0 resection, and are pathologically diagnosed with stage II-III gastric cancer.
• No preoperative neoadjuvant or adjuvant therapy received.
• Voluntary participation with signed informed consent, demonstrating good compliance and willingness to cooperate with follow-up procedures.
• Age between 18-75 years, with no gender restrictions.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.
• Estimated survival of 6 months or more.
• Baseline hematological and biochemical parameters within specified limits: a. Hemoglobin ≥ 80g/L. b. Absolute neutrophil count ≥ 1.5×10^9/L. c. Platelet count ≥ 100×10^9/L. d. Aspartate or alanine aminotransferase ≤ 2.5 times the upper limit of normal. e. Alkaline phosphatase ≤ 2.5 times the upper limit of normal. f. Thyroid-stimulating hormone (TSH) ≤ 1 times the upper limit of normal (if abnormal, T3 and T4 levels must be normal).

Exclusion criteria

• Pregnant or lactating women, or women of childbearing potential with a positive pregnancy test at baseline.
• Evidence of postoperative recurrence or metastasis.
• Previous anti-tumor therapy, including chemotherapy, radiotherapy, or immunotherapy.
• Positive resection margins identified in postoperative pathology.
• History of other malignancies within the past five years, except certain skin cancers, superficial bladder cancer, in situ cervical or breast cancer.
• Uncontrolled pleural effusion, pericardial effusion, or ascites.
• Severe cardiovascular conditions such as symptomatic coronary artery disease, congestive heart failure (grade ≥ II), uncontrolled arrhythmias, or myocardial infarction within the last 12 months.
• Uncontrolled infection, severe kidney disease, or other significant concurrent diseases.
• Allergic reactions to study drugs.
• Receipt of any anti-tumor therapy within 4 weeks prior to enrollment.
• Administration of live attenuated vaccines within 4 weeks prior to the first study treatment dose or plans to receive such vaccines during the study period.
• Positive HIV antibody, active hepatitis B or C (with specific viral load criteria).
• Positive for COVID-19 nucleic acid or antigen test.
• Other conditions deemed by the investigator to potentially affect patient safety or trial compliance, including serious illnesses requiring treatment, severe laboratory abnormalities, or other social or family reasons.