Based on the detection technology of methylation sites in feces, combined or not combined with Helicobacter pylori gastric cancer susceptibility gene detection, an early diagnosis and detection system for gastric cancer is established, and the clinical diagnostic value of the detection system is evaluated. In addition, the study observed the association between different loci and post-treatment recurrence, metastasis, or long-term survival rate through long-term follow-up of gastric cancer patients; Follow up with individuals with benign diseases such as gastritis and healthy individuals, compare cases of gastric cancer, and compare their sample data during follow-up with controls who did not have the disease.