Colorectal Cancer Screening in Chinese Rural Communities

Inclusion Criteria

1. Between 45 and 74 years old (inclusive).
2. Permanent resident within the geographic area covered by the screening program (typically defined as residing in the area for a minimum period, e.g., 6 months or more), and possessing local household registration (hukou) or residency documentation.
3. Self-reported absence of symptoms suggestive of colorectal cancer (e.g., rectal bleeding, change in bowel habits, abdominal pain, palpable abdominal mass, unexplained anemia, or unintentional weight loss).
4. No prior diagnosis of colorectal cancer or precancerous lesions (e.g., high-grade intraepithelial neoplasia, serrated lesions with dysplasia).
5. Not currently participating in another colorectal cancer-related clinical study that might interfere with the screening outcomes.
6. Willing and able to provide written informed consent, agreeing to participate in the screening program and comply with subsequent follow-up procedures (e.g., fecal testing, colonoscopy).

Exclusion Criteria

1. Previous diagnosis of colorectal cancer, history of resection of colorectal polyps (especially high-grade lesions or serrated lesions with dysplasia), or diagnosis of inflammatory bowel disease (ulcerative colitis, Crohn's disease).
2. Completion of a high-quality colonoscopy within a specified timeframe (e.g., within the past 1 year) with normal results (no polyps or only 1-2 tubular adenomas \<10mm), or completion of a high-quality sigmoidoscopy within a specified timeframe (e.g., within the past 3 years) with normal results.
3. Presence of severe comorbid conditions (e.g., severe cardiac, pulmonary, hepatic, or renal insufficiency) resulting in a life expectancy of less than 10 years, or physical condition unable to tolerate colonoscopy and bowel preparation.
4. Conditions such as severe coagulopathy, recent acute myocardial infarction or stroke (e.g., within the past 3 months), or severe psychiatric illness preventing cooperation.
5. Generally excluded due to safety considerations regarding screening colonoscopy during these periods.
6. Inability to understand the study content and provide informed consent due to cognitive impairment, language barriers, or other reasons.
7. Judged by the investigator to have a very high likelihood of being lost to follow-up during the study period, making completion of the screening pathway unlikely.