Development and Validation of Metabolic Biomarkers for Early Diagnosis, Prognosis, and Recurrence of Gastric Cancer：MetBio-GC

Inclusion Criteria: * \*\*Healthy Controls:\*\* 1. Age \> 18 years; 2. Signed informed consent and willingness to participate in the project. \*\*Gastric Cancer:\*\* 1. Age ≥ 18 years; 2. Performance status (ECOG) score ≤ 1; 3. Histopathologically confirmed gastric adenocarcinoma; 4. No family history of hereditary cancer; 5. No prior anti-tumor treatment; 6. Availability of primary tumor tissue from surgery or biopsy that meets submission requirements; 7. Availability of peripheral blood samples that meet submission requirements; 8. Willingness and ability to sign the informed consent form to participate in the study. Exclusion Criteria: * \*\*Healthy Controls:\*\* 1. Individuals at high risk for hereditary colorectal adenocarcinoma, including family members of the following diseases: family history of gastrointestinal tumors, familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC/LS), and Peutz-Jeghers syndrome (P-J syndrome); 2. History of chronic metabolic or inflammatory diseases that are difficult to control, such as hypertension, diabetes, chronic viral hepatitis, and inflammatory bowel disease; 3. Known history of other malignancies that have progressed or required treatment within the past 5 years, except for skin basal cell carcinoma and squamous cell carcinoma that have been cured; 4. History of oral or intravenous use of broad-spectrum antibiotics and probiotics within the past month; 5. Regular use of immunosuppressive drugs within the past 6 months; 6. Long-term use of other medications that may affect metabolism, such as hormones; 7. Inability or unwillingness to cooperate with follow-up visits and related examinations; 8. Inability to eat normally or requiring medications or enemas for bowel movements; 9. Presence of psychiatric disorders or other severe cardiovascular diseases; 10. Pregnant, breastfeeding, or planning to become pregnant within the next year; 11. Currently participating in an interventional clinical study or receiving study treatment that may influence the patient's treatment decision. \*\*Gastric Cancer:\*\* 1. Currently participating in an interventional clinical study or receiving study treatment that may influence the patient's treatment decision; 2. Known history of other malignancies that have progressed or required treatment within the past 5 years, except for skin basal cell carcinoma and squamous cell carcinoma that have been cured; 3. History of chronic metabolic or inflammatory diseases that are difficult to control, such as hypertension, diabetes, chronic viral hepatitis, and inflammatory bowel disease; 4. Presence of poorly controlled chronic comorbidities that may affect prognosis; 5. Presence of psychiatric disorders or other severe cardiovascular diseases; 6. Pregnant, breastfeeding, or planning to become pregnant within the next year; 7. Long-term use of medications that may affect metabolism, such as hormones, immunosuppressants, antibiotics, etc.; 8. Any severe and/or uncontrolled medical conditions, as judged by the investigator, that may affect the patient's ability to participate in the study or interfere with study results.