To explore the effects of bile reflux on gastric cancer and its precancerous lesions, so as to better prevent the occurrence and development of gastric cancer.

This study was a multicenter cross-sectional study. Patients were consecutively enrolled and divided into gastric cancer group, gastric precancerous lesions group, and chronic gastritis group, according to histopathological results. The bile reflux detection rate and Helicobacter pylori infection status were recorded for each group.

Inclusion Criteria:

1. Age 18 to 75 years old, gender is not limited;
2. patients with upper abdominal pain, abdominal distension, belching, anorexia, early satiety, hiccup, acid reflux, upper abdomen burning sensation and other upper gastrointestinal symptoms;
3. Voluntary acceptance of Hp testing;
4. Voluntary acceptance of the endoscopy and pathological biopsy.

Exclusion Criteria:

1. had undergone upper gastrointestinal surgery;
2. Previous diagnosis of esophageal cancer;
3. Previous diagnosis of gastric cancer;
4. Previous diagnosis of MALT lymphoma;
5. pregnant and lactating women;
6. Those with mental disorders;
7. Refusal to sign the informed consent form.

patients are from several centers all around the China