To explore the associations among bile acid profile, bile acid-microbiota cross-talk and the development of gastric cancer, so as to better prevent the occurrence and development of gastric cancer

This study is a case-control study. Patients, according to the pathological results, will be consecutively enrolled and divided into gastric cancer group, gastric precancerous lesions group, and chronic gastritis group. The serum and gastric juice bile acid profiles, gastric microbial composition of each group patients will be detected.

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.

patients are from Xijing Hospital