Stomach cancer has become one of the most common tumors in China, but unfortunately, early stage cancer has no symptoms and is mostly late when detected. However, our neighboring country, Japan, has the highest incidence of gastric cancer in the world and the world’s highest rate of early stage cancer diagnosis, which is over 80%. The reason for this lies in regular screening. In the outpatient clinic, we often encounter more than 50 patients who never have gastroscopy or other examinations, and their health awareness is very low. Although we often take time to do outpatient education and inform patients of the necessity of regular gastroscopy, the audience is too small after all. 1.Serum pepsinogen (PG) test PGI concentration and/or decrease in PGI/PGII ratio is suggestive for atrophic gastritis, usually PGI concentration ≤ 70ug/L and PGI/PGII ≤ 3.0 is used as the threshold value for the diagnosis of atrophic gastritis. PGII≤7.0. Gastric cancer risk classification Grade A: Patients with PG(-) and HPylori(-) may not undergo endoscopy; Grade B: Patients with PG(-) and HPylori(+) should undergo endoscopy at least once every 3 years; Grade C: Patients with PG(+) and HPylori(+) should undergo endoscopy at least once every 2 years; Grade D: Patients with PG(+) and HPylon: ( -) patients should undergo endoscopy once a year. PGI and PGI/PGII ratio are normal when atrophy is confined to the gastric sinus. Serum PG levels are more stable over a short period of time and the test can be repeated every 5 years or so. This part of the test is not for gastroesophageal junction cancer (cardia cancer). 2.Gastrin 17 (G-17) test Serum G-17 test can reflect the mucosal atrophy of the gastric sinus. The level of serum G-17 depends on the acidity of the stomach and the number of G cells in the gastric sinus. Therefore, fasting serum G-17 concentrations are lower in patients with high gastric acidity and sinusoidal atrophy. In combination with serum PG testing, serum G-17 concentration testing can diagnose atrophic gastritis in the gastric sinus (reduced G-17 levels) or confined to the gastric body only (elevated G-17 levels). Therefore, combined testing of serum G-17, PGI, PGI/PGII ratio and HPylori is recommended to increase the accuracy of assessing the extent and degree of gastric mucosal atrophy. 3.Barium meal of upper gastrointestinal tract Further endoscopic examination is performed if suspicious lesions such as decreased diameter of gastric lumen, stenosis, deformation, stiffness, indentation, niche shadow, filling defect, and mucosal fold changes are found on barium x-ray. 4.Endoscopic screening Endoscopy and endoscopic biopsy are the gold standard for the diagnosis of gastric cancer, especially the detection rate of flat type and non-ulcerous gastric cancer is higher than that of barium meal X-ray and other methods. It is a more feasible diagnostic strategy to use non-invasive diagnostic methods to screen out people with high risk of gastric cancer, followed by purposeful endoscopic precision examination.