Perhaps because of ethnicity, stomach cancer ranks third in the incidence of malignant tumors in China, while the highest incidence of malignant tumors among whites is lung cancer, prostate cancer and breast cancer, and the incidence of stomach cancer is extremely low. A survey found that the incidence of gastric cancer among Japanese Americans three generations later is also much lower than that of Japanese. Gastric bypass surgery was also invented by Americans, and although the distal part of the stomach cannot be observed after gastric bypass surgery, they do not have to worry about the occurrence of gastric cancer. Chinese, however, cannot ignore gastric cancer. If a patient has chronic atrophic gastritis, positive HP(+) for H. pylori disease, precancerous lesions such as intestinal epithelial metaplasia and gastric ulcer. Obese or diabetic patients with these diseases are generally not recommended to be gastric bypass patients because gastric cancer ranks third in the incidence of malignant tumors in China, and the distal stomach cannot be observed by gastroscopy after gastric bypass surgery. It leaves a great hidden danger for patients. Sleeve gastrectomy, instead of increasing the risk of gastric cancer, will reduce the risk because it can also remove the lesion areas such as mesenchymal tumor, gastric ulcer, intestinal epithelial hyperplasia, and atrophic gastritis on the side of the greater curvature of the stomach, in addition to implementing traditional gastroscopy for early detection of neoplastic gastric lesions.