Compared with Korea and Japan, our rate of early gastric cancer is very low, and most of the patients are already in the middle and late stage when they are found, so the treatment effect is greatly reduced. Korea and Japan also belong to countries with high incidence of stomach cancer, but their cure rate is much higher than ours, is it because foreign doctors do surgery better than Chinese doctors? No, it is because Korea and Japan have proper screening of gastric cancer, gastroscopy is more popular, and many newly detected gastric cancers are early stage gastric cancers, so the overall cure rate of gastric cancer is high and mortality rate is low. Moreover, there is no easy and effective diagnostic method to screen stomach cancer for the whole population. Endoscopy and other diagnostic methods for gastric cancer screening require a lot of labor and material resources, and because they are invasive examinations, many asymptomatic patients with low risk of developing gastric cancer find it difficult to accept them, and even developed countries with high incidence of gastric cancer such as Japan and Korea are unable to screen the entire population for gastric cancer. Therefore, screening for people with high risk of stomach cancer is the most effective method. Who should be screened more? The incidence of gastric cancer increases with age, and the incidence rate is lower in people under 40 years old. Most Asian countries set the age of 40-45 as the starting threshold age for gastric cancer screening, and in regions with high incidence of gastric cancer, such as Japan and Korea, the age of gastric cancer screening is advanced to 40 years old. In China, the incidence of gastric cancer among people over 40 years old has increased significantly, so it is recommended that 40 years old should be the starting age for gastric cancer screening. About half of the patients may have no alarm symptoms (gastrointestinal bleeding, vomiting, emaciation, upper abdominal discomfort, upper abdominal mass, etc.), and the proportion of patients under 45 years old with alarm symptoms is even lower, so screening should not be excluded because of no alarm symptoms. About 10% of gastric cancers show family aggregation, and the incidence rate of gastric cancer among relatives of gastric cancer patients is 4 times higher than that of those without family history of gastric cancer. According to the national situation and epidemiology of gastric cancer in China, those who meet any one of Article 1 + Article 2-6 should be listed as high-risk groups for gastric cancer and are recommended to be screened: 1.Age 40 years old or above, male or female; 2.People in regions with high incidence of gastric cancer, such as northwest (Qinghai, Ningxia, Gansu), northeast (Liaoning, Jilin, Heilongjiang) and southeast coastal areas of Jiangsu, Shanghai, Fujian, Zhejiang, etc. 3, people with H. pylori infection; 4, “old gastric disease”: previous chronic atrophic gastritis, gastric ulcer, gastric polyp, post-surgical residual stomach, hypertrophic gastritis, pernicious anemia and other pre-cancerous gastric diseases; 5, family history: first-degree relatives of gastric cancer patients; 6, long-term high-salt, pickled diet, smoking, heavy alcohol consumption and other dietary habits Upper gastrointestinal tract Barium meal examination In Japan, barium meal X-ray examination has been used since 1960 for screening of gastric cancer. Initially, 8 sets of small X-rays are used, and if there is any abnormality, 11 sets of more detailed X-rays are performed. If suspicious lesions such as reduced diameter of gastric lumen, stenosis, deformation, stiffness, indentation, niche shadow, filling defect, mucosal fold changes, etc. were found on barium X-ray examination, further endoscopic examination was performed. However, with the rapid development of endoscopic technology, endoscopy has basically replaced barium meal X-ray as the most common means of gastric cancer examination. In China, taking into account the actual situation of hospitals, barium meal X-ray of upper gastrointestinal tract can be considered as appropriate for gastric cancer screening. Endoscopic screening Endoscopy and its biopsy are currently the gold standard for the diagnosis of gastric cancer, especially the detection rate of flat and non-ulcerous gastric cancer is higher than that of barium X-ray meal and other methods. However, endoscopy depends on equipment and endoscopist resources, and it is relatively expensive, painful and poorly accepted by patients, even in developed countries such as Japan, endoscopy has not been used for mass gastric cancer screening. Therefore, non-invasive diagnostic methods to screen people at high risk for gastric cancer and then perform purposeful endoscopic screening are more feasible diagnostic strategies.