Adjuvant Serplulimab and Trastuzuma and Chemotherapy in Her-2+ Gastric Cancer

Inclusion Criteria: Lower age limit of research subjects 20 years old and upper age limit of 80 years old. Be proven to be primary adenocarcinoma of gastric cancer and staged II-III by pathological evidences R0 gastrectomy with D2 lymphadenectomy Her2+ diagnosed by Immunohistochemistry or FISH ECOG (ECOG score standard) performance status of 0 or 1 and expected to survive more than 6 months No contraindications, including normal peripheral blood routine, liver and kidney function and electrocardiogram （WBC≥3.5 x 109 /L, NEU≥1.2 x 109 /L,PLT≥90 x 109 /L and HGB≥80g/L). Exclusion Criteria: Patients with stage I and IV. Unavailable for R0 resection and D2 lymph node dissection. Multiple primary tumors Suffering from other serious diseases, including cardiovascular, respiratory, kidney, or liver disease, complicated by poorly controlled hypertension, diabetes, mental disorders or diseases. History of chemotherapy, radiotherapy, immunotherapy or target therapy.