Gastric cancer is a malignant tumor of the stomach, accounting for 95% of malignant tumors of the stomach and ranking first among gastrointestinal tumors, with more men than women. The etiology of gastric cancer is not yet completely clear. They include: Environmental factors: Studies have found that there is a certain coincidence between the distribution of gastric cancer and the distribution of geological formation and soil composition. In addition, there is also a relationship between gastric cancer incidence and socio-economic environment. Usually, the high incidence of gastric cancer in the low economic income class may be related to the high rate of H. pylori infection and the lack of fresh vegetables and fruits in the dietary structure. Diet structure and living habits: high salt, smoked and pickled foods are all risk factors for the development of gastric cancer. Smoking is one of the risk factors for the occurrence of gastric cancer. Survey statistics also show that the amount of fresh vegetables consumed is negatively correlated with the occurrence of gastric cancer. Some studies suggest that regular consumption of green tea may reduce the risk of stomach cancer. Genetic factors. About 5%-10% of gastric cancers have a tendency to gather in families, and 3%-5% are related to hereditary cancer syndromes. H. pylori: Studies have shown that H. pylori infection is related to the development of gastric cancer. However, it is believed that H. pylori is not a direct carcinogen of gastric cancer, and its exact carcinogenic mechanism is not clear. Precancerous state and precancerous lesion: precancerous state of gastric cancer is a clinical concept, which refers to pre-cancerous gastric diseases, including chronic atrophic gastritis, chronic gastric ulcer, gastric polyp, residual gastric state, etc.; precancerous lesion is a pathological concept, which refers to a category of histopathological changes of gastric mucosa prone to cancer, including gastric mucosal epithelial heterotypic hyperplasia and intestinal metaplasia, etc. These lesions are commonly found in precancerous gastric mucosal tissues. These lesions are commonly found in precancerous gastric mucosal tissues. It is generally believed that through this series of changes, intestinal gastric cancer eventually develops.