Exploration of a novel rbcDNA liquid biopsy technique for early detection of colorectal cancer is a promising development in the field of disease diagnosis and screening. This technique has the potential to establish an efficient and sensitive system for the early detection of colorectal cancer, which can provide a new perspective for individual health monitoring.

Patients who are at high risk of developing colorectal cancer and willing to undergo colonoscopy examination will be asked to collect a stool sample prior to bowel preparation for commercially available FIT (fecal immunochemical test) assay, as well as a blood sample for rbcDNA testing. The colonoscopy and histopathologic examination will be used as a reference for the results obtained from these tests.

Inclusion Criteria:

1. Age:40-74Years
2. Sex:All
3. Willing to provide written consent
4. Plan to undergo colorectaloscopy or surgical treatment and be able to provide a complete medical history and cooperate with blood sampling and follow-up visits，other operation.

For advanced adenomas (AA) group:

1. Adenomatous polyps with ≥25% villous component, high-grade dysplasia (HGD), or a diameter ≥10 mm were considered AA. Sessile serrated lesions with diameters ≥10 mm.
2. treatment-naive
3. No other comorbid tumors

For CRC group:

1. Confirmed CRC patients
2. treatment-naive
3. No other comorbid tumors

Exclusion Criteria:

1. Patients with colorectal cancer who have received prior treatment.
2. FAP (familial adenomatous polyposis), Crohn's disease, ulcerative colitis
3. Participants taking anticoagulants such as aspirin or warfarin, or those with coagulation disorders.
4. Prior history of colonoscopy within the past 5 years and removal of lesions
5. Pregnancy or intestinal infarction people
6. Unable to provide informed consent
7. Participants in other clinical trials or who have participated in other clinical trials within 60 days.
8. Unable to provide stool sample and follow-up visits.
9. Presence of major infectious diseases (e.g. HIV, etc.)

Subjects advanced adenomas and patients with confirmed CRC