Globally, there are more than 1 million new cases of gastric cancer each year, 400,000 in China, accounting for 42%, and about 800,000 deaths, accounting for 35% in China, which is one of the countries with the highest incidence and mortality rates of gastric cancer, and the incidence and mortality rates are more than twice the world average. About one Chinese dies of stomach cancer in 2 to 3 minutes, and the incidence of stomach cancer among young people aged 19 to 35 has doubled in the past 5 years compared to 30 years ago. Data show that among the top 10 cancers in China, stomach cancer has the second highest incidence rate and the third highest mortality rate, and its mortality rate accounts for about 25% of all malignant tumors. There are obvious geographical differences in the incidence of gastric cancer, and the incidence rate of gastric cancer in the northwest and east coast of China is significantly higher than that in the south. The high incidence of gastric cancer in people who consume fumigated and salted food for a long time is related to the high content of carcinogens or former carcinogens such as nitrite, fungal toxins and polycyclic aromatic hydrocarbon compounds in food; the risk of gastric cancer in smokers is 50% higher than that in non-smokers. Hp can promote the transformation of nitrate into nitrite and nitrosamine, which can cause cancer; Hp infection causes chronic inflammation of gastric mucosa plus environmental pathogenic factors accelerate the overproliferation of mucosal epithelial cells, leading to aberration and cancer; Hp toxicity products CagA and VacA may have cancer-promoting effects. The detection rate of anti-CagA antibodies in patients is significantly higher than that of the general population. The trauma caused by H. pylori in the stomach will make the stomach tissue more susceptible to the carcinogenic substances in cigarettes. 3.pre-cancerous lesions such as heterogeneous hyperplasia of gastric mucosa epithelium, chronic atrophic gastritis, gastric ulcer, gastric polyp, residual stomach after partial gastrectomy, etc. are prone to gastric cancer. 4.Genetic factors Staging 1.Early gastric cancer The lesion is limited to the mucosa or submucosa layer, regardless of the size of the lesion or the presence of lymph node metastasis. 2.Progressive gastric cancer Progressive gastric cancer is also called middle and late gastric cancer, and the lesion infiltrating the muscular layer is called middle gastric cancer and beyond the muscular layer is called late gastric cancer. More than 90% of gastric cancer patients in China are already in the progressive stage when they are diagnosed.