There are many causes of gastric cancer, and so far there is no exact cause, the most common ones may be the following. The first one is the infection of H. pylori. When the human stomach is infected with H. pylori, it can lead to lesions in the mucous membrane of the stomach, that is, the protective barrier of the stomach is destroyed, and after being destroyed, H. pylori can cause lesions in the stomach wall and lead to changes in the acid-base structure of the stomach. Over time, gastric cancer may occur in the stomach. Secondly, the change of stomach acid and the imbalance of acid-base balance can lead to lesions in the stomach, such as gastritis, which can lead to gastric cancer in serious cases. Thirdly, polypoid lesions in the stomach and chronic ulcers in the stomach may cause malignant changes after a long time. Fourth, hereditary factors, if there are immediate relatives in the family, such as parents or siblings or grandparents with stomach cancer, there may be a high incidence of stomach cancer. Fifth, the difference of diet, often eating pickled or salted food may lead to stomach cancer.