Stomach pain may be a precursor of stomach cancer. Stomach pain is one of the common clinical manifestations of gastrointestinal diseases, whether benign or malignant. However, the characteristics of stomach pain are very different. For benign gastric diseases such as peptic ulcer, stomach pain is usually regular and occurs mostly after eating or on an empty stomach, mainly as paroxysmal vague pain or dull pain, which can be relieved quickly by oral gastric medicine. Stomach pain caused by gastric cancer is usually irregular, with irregular episodes, not obviously related to diet, and mostly persistent upper abdominal vague pain, which cannot be significantly relieved by general gastric medicine. If a patient with benign gastric disease has recently changed the regularity of stomach pain and become irregular, and the effect of oral medication that used to be effective is not obvious now, it may be a precursor of stomach cancer. Because some benign gastric diseases, such as gastric ulcer, chronic atrophic gastritis, reflux esophagitis, etc., are mostly considered as precancerous lesions of gastric cancer and have certain risk of becoming gastric cancer.