This is a prospective study designed to evaluate the efficacy of a multi-target fecal DNA test for the early detection of gastric cancer. The test combines Helicobacter pylori gene detection with analysis of fecal methylated DNA markers. The primary objective is to assess whether each method, individually or in combination, can facilitate earlier diagnosis of gastric cancer. All participants will undergo the multi-target fecal DNA test and complete the gastric cancer risk questionnaire.

Sample Selection:

The study will be conducted in selected communities within Tongling City, with a total of 10000-15000 residents recruited

Participants Recruitment:

• Participation is voluntary. All subjects must provide written informed consent at the time of recruitment.
• Well-trained investigators will conduct face-to-face interviews to administer the gastric cancer risk questionnaire.

Tests and Follow-up:

• Initial Screening: All participants will provide a stool sample for the multi-target DNA analysis (including H. pylori susceptibility testing and methylated DNA markers) and complete a questionnaire.
• Definition of Screening Positive: A participant will be considered screening positive if they test positive on the fecal multi-target DNA test or are identified as high-risk through the questionnaire.
• Diagnostic Workup: All screening-positive individuals will be referred for a confirmatory diagnostic workup. Briefly, the endoscopist will conduct a fiberoptic endoscopy and perform a pathological biopsy.
• Follow-up: Screening-positive individuals who are not diagnosed with gastric cancer in the first year will be entered into an annual follow-up program.
• Biobanking: Residual fecal samples will be stored at the biobank of Fudan University Shanghai Cancer Center for future biomarker research.

Inclusion Criteria:

1. Age ≥40 years, male or female.
2. No contraindications to endoscopy and able to cooperate with endoscopy.
3. Patients must be able to fully understand the informed consent form and be able to sign the informed consent form in person.

Exclusion Criteria:

1. A history of diagnosed gastric cancer or other malignant tumors of the digestive tract.
2. Comorbid severe underlying conditions (e.g., severe cardiopulmonary insufficiency, liver or renal failure, etc.) that are likely to result in a short life expectancy or render long-term follow-up impractical.
3. Severe mental illness or incapacity to participate in the study due to lack of civil behavior.
4. Pregnant or breastfeeding women.
5. Other conditions that the investigator deems inappropriate for participation in the study.

Subjects were recruited mainly from communities in Tongling, Anhui Province. The subjects were identified by the investigator based on the enrollment criteria and were informed about the contents of the informed consent form.