1. Over 40 years old with a history of chronic gastric disease or recent indigestion. We found that there is a certain connection between atrophic gastritis, gastric polyp or chronic gastric ulcer and gastric cancer, and the incidence of gastric cancer in people with these diseases is higher than normal people, and the incidence of gastric cancer is also higher in countries and regions with high incidence of these diseases. 2.People with family history of stomach cancer or esophageal cancer. The role of genetic factors in the development of gastric cancer is relatively certain, and gastric cancer has the tendency to gather in families, and gastric cancer occurs in several generations in some families, and all of them are immediate relatives. People with a family history of gastric cancer are four times more likely to develop gastric cancer than normal people. Some studies have reported that Napoleon died of stomach cancer, while his grandfather, father and three sisters also suffered from stomach cancer. This shows that there is a clear genetic component to stomach cancer. Although some scholars point out that this may also be the result of the same environmental factors and similar lifestyle habits acting on family members. However, most scholars still believe that the role of genetic factors in the development of gastric cancer is relatively certain. 3.People who like high salt diet (including pickled products) and smoked foods. Some chemicals in cured and smoked foods (such as nitrite, polycyclic hydrocarbons, phenolic compounds, etc.) can stimulate the gastric mucosa and make it become cancerous. Recent studies have shown that excessive salt intake not only increases the likelihood of cardiovascular diseases, but also may be a cancer-causing and cancer-promoting factor for gastric cancer. On the contrary, the vitamins in vegetables and fruits have an inhibiting effect on the occurrence of stomach cancer. The fact that the incidence of stomach cancer in the south of China is significantly lower than that in the north may be related to the high temperature and abundant rainfall in the south, which provides fresh and diversified vegetables and fruits in all seasons. 4. Long-term alcoholics and smokers. Although alcohol itself has no carcinogenic effect, it can damage the gastric mucosa, and alcohol also acts as a solvent for many harmful compounds, which increases the absorption of them by the body. In addition, it is clear that the more you smoke, the greater the risk of stomach cancer. Therefore, smoking cessation has been proposed as a preventive measure for gastric cancer.