The development of gastric cancer is from chronic superficial gastritis - chronic atrophic gastritis - intestinal epithelial hyperplasia - heterogeneous hyperplasia - gastric cancer. Therefore, actively preventing and treating chronic gastritis and other pre-cancerous diseases, especially actively treating atrophic gastritis and intestinal epithelial hyperplasia, is an important preventive measure to avoid gastric cancer. Pre-cancerous disease of stomach cancer is a disease in which people have more chances to develop stomach cancer than other people. However, having precancerous disease does not mean that all of them will develop cancer in the future, and only some of them will become cancerous. Chronic Atrophic Gastritis In chronic atrophic gastritis, low stomach acid favors the reproduction of nitrate-reducing bacteria, which reduces nitrate in food to nitrite, which combines with amine to form carcinogenic nitrosamines. Especially in chronic atrophic gastritis, the possibility of developing into gastric cancer is greater, but the time needed is longer. Some people have followed up and observed that gastric cancer occurs in about 10% of chronic atrophic gastritis, especially atrophic gastric sinusitis with intestinal metaplasia and atypical hyperplasia, which is susceptible to cancer. It is generally believed that intestinal chemosis type II or incomplete type, resembling colonic mucosa and cup cells, secreted by sulfated mucin, is prone to cancer. Chronic atrophic gastritis has a long course, and some patients have dyspeptic manifestations, i.e., epigastric fullness and discomfort (especially after meals), irregular abdominal pain, belching, acid reflux, nausea and vomiting. Most of them do not have obvious signs, sometimes there can be light pressure pain in the upper abdomen, etc. Gastric body gastritis can have tongue inflammation and anemia in severe cases. Gastric polyps There are two types of gastric polyps: hyperplastic and adenomatous. Gastric adenomatous polyps are rare, but prone to malignant transformation, literature statistics about 20% of adenomatous polyps transformed into gastric cancer, especially the tendency of multiple polyps more than 2cm to become cancerous has increased, and it is often regarded as precancerous disease. Polyps usually develop at an older age, more between 55 and 75 years old, mostly in men. Early symptoms are often mild pain and discomfort in the upper abdomen, such as larger polyps obstructing the pyloric canal or sliding into the duodenum, pyloric obstruction symptoms appear, because such patients are often accompanied by a lack of gastric acid or low gastric acid, so nausea, anorexia, dyspepsia, weight loss, diarrhea, etc., are often more pronounced. Intermittent bleeding may occur if polyps have erosions and ulcers on the surface. Gastric ulcer Most medical researchers believe that some gastric cancers can be malignant from gastric ulcers, but the incidence is low. According to some studies in Shanghai and Beijing, gastric cancers malignant from gastric ulcers are 1%~5%. Cancer occurs at the edge of ulcer. Chronic gastric ulcers, aged above 45 years old, with symptoms becoming persistent and ineffective after a month or so of strict medical treatment, and at the same time, fecal occult blood test becomes positive, it should be considered that the ulcers have the possibility of cancerous transformation, and it is necessary to make further examination and multi-point biopsy at the edge of the ulcers to make clear the nature of the ulcers. Stomach remnant After gastrectomy, the cancer rate of stomach remnant is two times higher than that of normal people, and it usually takes 15~30 years, because the bile reflux after operation causes gastric atrophic gastritis, which constitutes the basis of cancer, plus the abnormal reproduction of cells due to lack of acidity, which promotes the transformation of carcinogenic substances such as secondary amines or nitrites into the form of nitrosamines, and the bile salts in the bile itself also have carcinogenic effects. Therefore, the residual stomach is also regarded as a precancerous disease.