Gastric precancerous lesions and gastric cancer Gastric cancer is one of the common malignant tumors, and its incidence and mortality rate are the first among malignant tumors in China. Like other malignant tumors, the carcinogenesis of gastric mucosal epithelium is a gradual process, which often goes through years of continuous precancerous stage of gastric cancer, and a few patients will evolve into gastric cancer. At present, the appearance of non-colonic intestinal hyperplasia or moderate or severe atypical hyperplasia in gastric mucosa is regarded as precancerous lesion of gastric cancer. Atypical hyperplasia is heterogeneous hyperplasia, which is mainly abnormal proliferation of epithelial cells and glandular cells and loss of original function, and can be classified into 3 grades: mild, moderate and severe. Intestinal hyperplasia comes from the proliferating cells of the glandular neck, which is type small intestinal hyperplasia, an inflammatory reaction, and not type colonic hyperplasia, which is closely related to the occurrence of intestinal gastric cancer. Therefore, when the pathological report is atypical hyperplasia (mild) in gastric mucosa or type small intestinal hyperplasia in gastric mucosa, it is not a precancerous lesion of gastric cancer and the possibility of cancer is very small. If the pathological features are: moderate or severe atypical hyperplasia of gastric mucosa or untypical colitis of gastric mucosa, it is a precancerous lesion of gastric cancer and has the possibility of cancer. Therefore, it is necessary to clarify the diagnosis. The reversal of precancerous lesions of stomach is an important measure to prevent stomach cancer. In the treatment of precancerous lesions, after protecting mucosa, improving blood circulation of gastric mucosa and increasing regeneration and repair function of gastric mucosa epithelial cells, generally chronic atrophic gastritis can be transformed into chronic superficial gastritis or restore normal mucosa; the number of intestinal chemosis can also be reduced or disappeared. According to our research, mild and moderate atypical hyperplasia can be reversed, but the chance of reversing or disappearing severe atypical hyperplasia is small, and about more than half of them can be transformed into gastric cancer.