1, chronic gastritis: mainly refers to: chronic atrophic gastritis, the development of chronic atrophic gastritis has a process, namely chronic superficial gastritis → atrophic gastritis → intestinal epithelial hyperplasia → heterotypic hyperplasia → gastric cancer, its cancer rate is 2% to 10%, atrophic gastritis and cancer-related factors can include: ① lesion site, the cancer rate of gastric sinus gastritis can be as high as 10%, higher than that of gastric body gastritis; ② whether there is intestinal epithelial hyperplasia, patients with intestinal hyperplasia can evolve into gastric cancer; ③ the degree of heterotypic hyperplasia, mild to moderate heterotypic hyperplasia cancer rate is low, severe heterotypic hyperplasia can evolve into gastric cancer. (2) whether there is intestinal epithelial hyperplasia, the cancer rate is higher in patients with intestinal hyperplasia; (3) the degree of heterotypic hyperplasia, the cancer rate of mild to moderate heterotypic hyperplasia is low, while severe heterotypic hyperplasia can evolve into gastric cancer. 2.Gastric ulcer, at present, there are different clinical opinions on the cancer of gastric ulcer, but it is mostly believed that cancer may occur, but the chance of cancer is not high, about 1% or less. 3.Gastric polyps: Among the two histological types of gastric polyps, adenomatous polyps can develop into adenocarcinoma, and hyperplastic polyps have a lower chance of carcinogenesis. 4.Residual gastritis and residual gastric ulcer: residual stomach: With the widespread implementation of partial gastrectomy, the incidence of residual gastric cancer has gradually increased, especially in patients operated by Billroth-II style. The causes may be: reflux of bile and pancreatic juice, which causes atrophic gastritis in the remnant stomach, and decrease of gastric acid, leading to abnormal multiplication of bacteria in the stomach, which eventually transform secondary amines or nitrites into nitrosamines and cause carcinoma. 5.Other: internal gastric schistosomiasis, pernicious anemia.