For patients with early gastric cancer or called early gastric cancer, most of them have no clinical symptoms, so they will not have obvious pain, let alone frequent stomach pain, and some of them may only show non-specific gastrointestinal symptoms, such as vague pain in the upper abdomen, bloating, acid reflux, belching and so on. However, the above symptoms are often ignored by patients or not taken seriously, so most of them will not take the initiative to do electrogastroscopy. It is possible that no obvious lesions are found even after gastroscopy, which may lead to missed diagnosis. In case of progressive gastric cancer or advanced gastric cancer, there will be recurrent pain and irregular stomach pain, accompanied by clinical symptoms such as poor appetite, anorexia, emaciation, anemia and black stool.