The exact cause of gastric cancer is not very clear, but the following factors are related to its development: 1. geographical environment and dietary and living factors
There are obvious geographical differences in the incidence of gastric cancer, and the incidence rate of gastric cancer in northwest and eastern coastal areas of China is significantly higher than that in southern areas. The high incidence of stomach cancer in people who consume smoked 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 lack of fresh vegetables and fruits in food is also related to the incidence. The risk of gastric cancer in smokers is 50% higher than that in non-smokers. 2.H. pylori infection
Helicobacter pylori (Hp) infection is also one of the main factors triggering gastric cancer. The HP infection rate of adults in the high incidence area of gastric cancer in China is over 60%, which is significantly higher than the HP infection rate of 13%-30% in the low incidence area. HP infection causes chronic inflammation of gastric mucosa plus environmental pathogenic factors that accelerate the overproliferation of mucosal epithelial cells, leading to aberrations and tumors. The role of infection control in the prevention and treatment of gastric cancer has been highly emphasized. 3.Pre-cancerous lesions
Precancerous lesions refer to benign gastric diseases and pathological changes that increase the risk of developing gastric cancer. Gastric diseases that are prone to gastric cancer include gastric polyps, chronic atrophic gastritis and residual stomach after partial gastrectomy, all of which may be accompanied by chronic inflammatory process of different degrees, intestinal epithelial hyperplasia or atypical hyperplasia of gastric mucosa. There is a risk of transformation to cancer over time. Gastric polyps can be divided into inflammatory polyps, hyperplastic polyps and adenomas, the possibility of malignancy of the first two is very small, while the cancer rate of gastric adenomas is about 10%-20%, and the chance of cancer increases when the diameter exceeds 2cm. Preneoplastic lesions refer to the histological changes of gastric mucosa that are prone to carcinogenesis and do not have malignant characteristics yet, but are junctional pathological changes in the process of transformation from benign epithelial tissue to cancer. The heterogeneous hyperplasia of gastric mucosal epithelium is a precancerous lesion, which can be classified as mild, moderate or severe according to the degree of cell heterogeneity (currently described as low-grade, high-grade intraepithelial neoplasia), and it is sometimes difficult to distinguish severe heterogeneous hyperplasia from well-differentiated early gastric cancer. 4.Genetic susceptibility factors
Gastric cancer has obvious tendency of family aggregation, and the family incidence rate is 2-3 times higher than that of the population. The most famous example of Bonaparte family well illustrates the role of genetic factors in the development of gastric cancer, as Napoleon, his father and grandfather all died of gastric cancer.