Why should we insist on post-operative review? With the continuous progress of medicine, the treatment of GI malignant tumors has developed from a single radiotherapy or surgery to a comprehensive system. For patients who have undergone surgical treatment, adhering to standardized postoperative observation and review is also a very important and indispensable part of the tumor treatment process. Regular and standardized postoperative review plays an important role in the treatment of the disease. 1. Evaluate the possible side effects of treatment Since the surgery of GI malignancy usually needs to change the structure of GI tract itself (such as subtotal resection of stomach or colostomy after colorectal cancer surgery), patients may have GI symptoms such as abdominal distension, diarrhea, abdominal pain and even some systemic symptoms after surgery. The causes behind these seemingly identical discomfort symptoms may be different. For example, some patients may suffer from functional disorders due to fast eating, while others may suffer from organic changes due to intestinal obstruction caused by intra-abdominal adhesions after surgery. In addition, some patients require adjuvant therapy such as radiotherapy, chemotherapy and immunotherapy after surgery, and these treatments may be accompanied by mild or severe complications. Therefore, in order to comprehensively assess the postoperative recovery of patients and to be able to receive timely treatment of the disease, it is recommended that patients be reviewed regularly and regularly. 2. Early detection of recurrent foci with the possibility of resection and cure, or diagnosing new heterochronous tumors before they infiltrate Patients with progressive and some early gastrointestinal malignancies, despite radical surgery, some patients still have recurrence and metastasis after surgery. And regular postoperative comprehensive review and follow-up can help patients to detect new lesions in time. Studies have proved that if new lesions can be detected early and excised completely, it does not affect the expected survival of patients after surgery. 3.Avoid unnecessary doubts Many patients with gastrointestinal malignancy will have various doubts after surgery. Compared with various sources, the guidance obtained from regular hospitals and doctors is more informative and more in line with the principle of individualized treatment. Time and content of postoperative review Evidence shows that postoperative recurrence of patients with gastrointestinal malignancies mostly occurs within the first 1-3 years after surgery, therefore, patients should be reviewed relatively frequently within the first 3 years after surgery. after 3 years, the interval of review can be relatively extended. The specific follow-up time and content vary slightly according to the type of disease. 1.Scheduling: Patients should be reviewed every 3 months for the first 3 years after surgery and once every 6 months afterwards. (1) Physician’s history and physical examination: new onset of abdominal pain, appetite change, rapid weight loss and other symptoms should be alert; (2) blood tests: blood routine, liver and kidney function, gastrointestinal tumor markers; (3) imaging: abdominal ultrasound, chest X-ray, further review of CT if there are abnormalities; (4) gastroscopy: review of gastroscopy within 1 year after surgery, and annually thereafter. Gastroscopy: Gastroscopy was repeated within 1 year after surgery and once a year thereafter. The purpose of the first gastroscopy is to assess the postoperative recovery, and thereafter gastroscopy is for early detection of tumor recurrence. It is reported that the combination of CEA and CA19-9 can significantly compensate the shortage of single test and improve the detection rate of recurrence and/or metastasis after gastric cancer surgery, and the false positive rate is only 15.38%.