First of all, chronic atrophic gastritis can turn into gastric cancer, especially when chronic atrophic gastritis develops intestinal hyperplasia and heterogeneous hyperplasia, the chance of cancer is very high. For patients with chronic atrophic gastritis in this period, they need to cooperate with the doctor to give preventive surgery in time. Secondly, gastric polyp is also a precancerous disease of gastric cancer. For inflammatory polyp, it is almost not cancerous, but adenomatous polyp has a very high chance of becoming cancerous, especially the broad-based polyp with diameter >2cm. There are also gastric ulcers, and cancer can occur in a small number of gastric ulcers, and the cancer mainly occurs at the edge of the ulcer. In addition, residual gastritis may also become cancerous 10-15 years after gastric cancer surgery. Therefore, it is recommended that patients should be closely followed up for the above diseases, and if necessary, active treatment should be given in cooperation with doctors.