A Study on Gastrointestinal Cancer Screening Using a Multi-Targeted Combined Detection Model: A Multicenter, Prospective, Randomized Controlled Trial

INTERVENTION: Intervention Group:Combined Testing Using a "Multi‐Target Blood Methylation + Fecal FIT + Fecal Calprotectin" Model;Control Group:Routine observation and follow‐up ; CONDITION: Gastrointestinal Cancers PRIMARY OUTCOME: Differences in cancer‐specific mortality rates for tumors of the entire gastrointestinal tract between the two groups; SECONDARY OUTCOME: The incidence of gastrointestinal cancer in the two groups; The sensitivity and specificity of the combined screening model for detecting gastrointestinal cancer in the intervention group;All‐cause mortality rates in the two groups;Detection rates of precancerous lesions and early‐stage gastrointestinal cancers;Complications associated with endoscopic screening, primarily including potential bleeding, perforation, infection, cardiovascular and cerebrovascular complications, aspiration, or screening‐related deaths; INCLUSION CRITERIA: 1. Participants must be between 45 and 74 years of age at the time of enrollment; 2. Participants must be scheduled to undergo gastrointestinal endoscopic screening; 3. Participants must agree to undergo a five‐year follow‐up as specified in the protocol; 4. Participants must be willing to participate and sign an informed consent form.