This is a prospective, case-control study intended to develop and validate a blood-based multi-omics assay and computational model for early detection of gastric cancer. Approximately 450 subjects who receive esophageogastroscopy (EGD) will be enrolled and assigned to three arms including gastric cancer, precancerous lesion, and healthy control based on the diagnosis of EGD and histological results. Cell free DNA will be extracted from peripheral blood of all participants and assayed by next-generation sequencing for biomarkers including somatic mutation, methylation, and chromosome instability signals. In the first stage a multi-omics models will be developed for classification between malignancy group and control groups, and between precancerous group and healthy control. Sensitivity and specificity of the model will be evaluated in an independent validation group in the second stage.

Inclusion Criteria:

• Age≥40
• Received EGD;
• Subjects must have given written informed consent, and the subjects compliance are good.

Exclusion Criteria:

• Subjects who could not accept EGD;
• Subjects who had previously undergone total or partial gastrectomy;
• There are other serious acute or chronic medical or mental diseases or laboratory abnormalities that may interfere with the interpretation of the research results and make the subjects unsuitable for the study in the judgment of the researchers;
• Subjects with a history of malignant tumor or two or more malignant tumors at the same time;
• Pregnant subjects;
• Subjects who had a history of bone marrow or organ transplantation, or had a history of blood transfusion one month before enrollment.
• The subjects with incomplete clinical data collection or other reasons judged by the researchers are not suitable for this study.

Subjects aged≥40 who will receive EGD.