Clinical Research Directory

Inclusion Criteria: * Study population signing informed consent form * Age: 18-75 years old * The study population must underwent endoscopic examination and was confirmed by pathological diagnosis as gastric cancer: including high-level intraepithelial neoplasia, early gastric cancer, and advanced gastric cancer. Exclusion Criteria: * Those who have undergone gastrointestinal surgery within the past 1 year; Patients who have undergone neoadjuvant chemotherapy and have developed tumors in the residual stomach after previous partial gastrectomy. * Those who have used proton pump inhibitors, antibiotics, probiotics, and prebiotics daily within the past month, and those who have recently received hormone therapy. * People with infectious diseases and other digestive system diseases that interfere with the experimental results, such as inflammatory bowel disease, irritable bowel syndrome, etc.