Staging of gastric cancer is also the severity of the disease we are talking about, which directly affects the treatment mode, effect and prognosis. Staging includes preoperative staging and postoperative pathological staging, among which the depth of tumor invasion (T), lymph node metastasis (N) and distant metastasis (M) are important indicators of staging. Often, the accurate staging is difficult to know before surgery. We do chest X-ray, ultrasound, CT, ultrasound gastroscopy and even PET-CT to know whether there are obvious distant metastases, and try to know the preoperative staging of the patient to decide whether to operate or not. However, any examination has a certain rate of leakage, and it is impossible to detect some diffuse lesions <1cm, so the only way to know whether it can be opened and clean is to open the stomach. Nowadays, laparoscopic technology can clearly magnify the organs in the abdominal cavity without opening the abdominal cavity by "punching holes" in the abdominal wall, so as to understand whether the tumor has spread or not and provide more accurate staging without affecting the patient's recovery. The exploration at the beginning of the surgery determines the scope and modality of the surgery. The main types of surgery are: radical, palliative and unresectable. If the tumor has not yet broken through the stomach wall and invaded outside the stomach, radical gastrectomy can be done, and the amount of gastrectomy depends on the size and location of the tumor. With the progress of modern medicine, there is basically no difference between partial gastrectomy and total gastrectomy in terms of surgical safety, postoperative nutrition and recovery. If the tumor invades other organs outside the stomach, the decision of whether the tumor can be removed depends on the type and extent of the invading organs and whether there is distant spread. The invasion of resectable organs such as spleen, tail of pancreas, transverse colon and part of the left lobe of liver can be resected radically by combined organ resection, but the trauma of the operation and the possibility of postoperative complications are increased accordingly. The invasion of unresectable organs such as the head of the pancreas, the mesenteric root of the transverse colon, and important blood vessels can only be done with residual palliative resection; if the invasion is severe and cannot be separated, the tumor may not be removed. If a rice-like tumor is found to have spread in the abdominal cavity and the local tumor can be resected, the local tumor can be removed (palliative resection) to reduce the tumor load and the complications of bleeding, perforation and obstruction that the tumor may cause, to provide assurance for future chemotherapy and to improve the quality of life. The complete pathology report about 1-2 weeks after surgery can give more detailed pathological stages such as the depth of tumor invasion (T), lymph node metastasis (N), distant metastasis (cancer nodules), the presence of tumor in blood vessels (vascular cancer thrombus), the presence of tumor invasion of nerves and the cutting edge. The prognosis after radical surgery for gastric cancer with different pathological stages is different (see the figure below). Even for early gastric cancer with successful surgery, recurrence and metastasis are still possible after surgery. Once there is lymph node metastasis, chemotherapy is generally needed, but it still needs to be combined with the patient's age and physical condition. The timing of chemotherapy is generally decided 1-2 weeks after discharge from the hospital and after the patient's body recovers.