Associations Among Serum and Gastric Juice Bile Acid Profile, Bile Acid-microbiota Cross-talk in Stomach and the Development of Gastric Cancer

Inclusion Criteria: 1. Age 18 to 75 years old, gender is not limited; 2. No history of antibiotic or probiotic use for 8 weeks; 3. No preoperative chemotherapy or radiation therapy prior to the examination; 4. Voluntary intravenous blood collection, gastroscopy, extraction of gastric juice and pathological biopsy. 5. Voluntary testing for H. pylori Exclusion Criteria: 1. had undergone upper gastrointestinal and colon surgery; 2. Previous diagnosis of Malignant Tumors; 3. Presence of a disease or medication that affects bile acid metabolism, such as endocrine or autoimmune diseases; 4. Recent use of drugs that affect gastrointestinal motility; 5. Presence of contraindications to endoscopy; 6. pregnant and lactating women; 7. Those with mental disorders; 8. Refusal to sign the informed consent form.