Gastric Cancer, Adenocarcinoma

The purpose of this clinical trial is to investigate whether the drug Shenqi Fuwei Mixture is effective for postoperative recurrence and metastasis of gastric cancer. Safety of Shenqi Fuwei Mixture will also be understood. It aims to answer the main questions: * Shenqi Fuwei Mixture in perioperative combined with neoadjuvant chemotherapy to reduce the recurrence and metastasis of locally advanced gastric cancer after surgery? * Shenqi Fuwei Mixture in the prevention and treatment of postoperative recurrence and metastasis of gastric cancer dominant population characteristics and efficacy mechanism? * Exploratory excavation of TCM syndrome, multi-omics combined means to explore the advantages of Shenqi Fuwei Mixture on postoperative recurrence and metastasis of gastric cancer? The researchers will compare the drug Shenqi Fuwei Mixture with placebo (a substance that does not contain drugs and has a similar appearance) to see if the drug Shenqi Fuwei Mixture can prevent and treat recurrence and metastasis of gastric cancer after surgery. Participants will: * Take Shenqi Fuwei Mixture or placebo daily, synchronize with chemotherapy, or until tumor progression or intolerable toxicity * Visits every 3 weeks for tests and tests * Their survival status and adverse drug reactions were recorded