Gastric cancer has a genetic tendency, and gastric cancer has a family aggregation tendency. Previous studies have suggested that environmental factors may be the main cause of the occurrence and prevalence of gastric cancer, but heredity and immunity play a certain role in the formation of gastric cancer. The research results of 752 cases of gastric cancer in 9 cities in China, including Beijing, Shanghai, Xi and Fuzhou, show that the incidence of gastric cancer in people with family history of cancer is greatly influenced by environmental factors, while diffuse gastric cancer is closely related to family. At present, gastric cancer is on the decline in many countries. The results of investigation and analysis show that intestinal gastric cancer decreases rapidly with time, while diffuse gastric cancer decreases slowly. The inheritance of gastric cancer is a family genetic phenomenon of cancer caused by chromosome aberration. At present, it is thought that it may be caused by chromosome aberration, which is sometimes passed on to future generations, but this inheritance is not a direct cancer inheritance, but an individual's tendency to develop cancer. When the immune function is low or defective, the susceptibility to gastric cancer can be increased, and the mutant cells can not be eliminated in the bud in time, which leads to gastric cancer. People with type A blood are more likely to suffer from gastric cancer. ABO blood group research shows that gastric cancer is related to type A blood, but only to diffuse gastric cancer. Correa report 164 cases of diffuse gastric cancer, 49% were type A blood, accounting for 38.3%. It is a genetic tendency that diffuse gastric cancer is related to type A blood. In recent years, with the application of molecular genetics in human cancer research, people gradually realize that cancer is dominated by activated cell genes. This is essentially due to the mutation of some genes, which destroys the coordination of controlling and regulating normal cell growth and development, thus leading to abnormal cell reproduction. However, the role of genetic factors in the etiology of human gastric cancer is difficult to study and needs further study. Studies on genetic immunity and epidemiology of gastric cancer suggest that environmental factors may be the main cause of the occurrence and prevalence of gastric cancer, and genetics and immunity also play a role in the formation of gastric cancer. 1980 Correa divides gastritis into autoimmune type, hypersecretion type and environmental type from the epidemiological point of view. It is believed that autoimmune type is mainly related to immune mechanism, and pernicious anemia often occurs. The lesions mainly involve the fundus and body of the stomach, which often leads to total stomach atrophy in the later stage and has a genetic tendency. According to the investigation in Colombia, chronic atrophic gastritis conforms to the law of autosomal negative inheritance, and the incidence of chronic atrophic gastritis is greatly influenced by age and mother. In the population studied, the gene carrying rate of atrophic gastritis was 6 1%. If the mother is a patient, 72% of the children will also suffer from atrophic gastritis at the age of 0. If the mother is normal, the prevalence rate of children is 4 1%. It is also found that pernicious anemia with diffuse gastritis belongs to autosomal dominant inheritance. Genetic immune disorder may be one of the internal causes of gastric cancer. In 1985, Kihies et al. studied 377 patients with primary low r- globulinemia and found that the incidence of gastric cancer was 47 times higher than that of normal people. The deficiency of immune monitoring function can increase the susceptibility of gastric cancer. When cellular immunity is deficient, tumors are prone to occur, especially after gastric mucosal amine injury. Due to low or defective immune function, mutant cells can not be eliminated in the bud in time, leading to gastric cancer. It is generally believed that gastric cancer is polygenic, but it is difficult to study the role of genetic factors in the etiology of human gastric cancer, and there are still some methodological problems that need further exploration. ]