Inclusion Criteria:

- Healthy registered inhabitants from 10 villages in a high-risk county of gastric
cancer in China

- Age 30-59 years

- A willingness to participate in the study as indicated by written informed consent

Exclusion Criteria:

- Severe concomitant illness (eg, severe hypertension, coronary heart disease, diabetes
mellitus, stroke, asthma, liver cirrhosis, tuberculosis, infectious hepatitis, and
cardiac, respiratory, hepatic, or renal insufficiency)

- Patients with epilepsy or severe mental illness

- Previous diagnosis of cancer

- A history of esophageal or gastric surgery

- Drug abuse and drug dependence

- Allergic to omeprazole, amoxicillin, or clarithromycin

- Pregnant and lactating women

- Previous history of H pylori eradication treatment

- A negative 13C-urea breath test (UBT)

- A definite indication of H. pylori eradication (eg, gastric or duodenum ulcer)

- Dysplasia or carcinoma lesions are found in esophageal or gastric histopathological
examination

- Other factors or conditions might influence the results of study