The DNA methylation targets in preoperative plasma samples of the subjects will be detected by the multi-gene methylation test (ColonAiQ), and the test accuracy will be evaluated by compared with the clinical diagnosis evidence.

The accuracy of ColonAiQ test in clinical testing will be evaluated in the multicenter, prospective study. Patients with colorectal cancer, intestinal polyps, adenomas and other non-neoplastic diseases of the digestive system, and patients with non-colorectal cancer such as gastric cancer, esophageal cancer, breast cancer and lung cancer will be enrolled. In this study, all cfDNA will be tested by fluorescence quantitative PCR, and some samples will be tested by NGS to verify the effectiveness of ColonAiQ test. Clinical diagnosis reports and methylation test results will be blinded to the lab tester and clinician respectively.

Inclusion Criteria:

1. Age ≥18 years old, gender is not limited;

2. meet one of the following conditions: 1) Suspected colorectal cancer (CRC); 2) Diagnosed with CRC according to clinical diagnostic criteria; 3) Do not have CRC and have interfering diseases:

   1. Confirmed non-CRC digestive tract cases: colorectal polyps, adenomas, and other benign diseases of the digestive system;
   2. Confirmed cases of other cancers other than CRC: gastric, esophageal, breast, and lung cancer;
   3. diseases where the same gene methylation may be present (non-rheumatoid arthritis, etc.);

3. The subject or his/her guardian is able to understand the purpose of the study, demonstrate sufficient adherence to the study protocol, and sign the informed consent.

Exclusion Criteria:

1. People who cannot tolerate relevant tests for clinical diagnosis;
2. Pregnant women;
3. Patients who have previously received colorectal cancer surgery, tumor drug therapy, neoadjuvant therapy, or radiotherapy;
4. Other conditions deemed unsuitable for inclusion by the investigator.

Subjects 18 years of age and older who are eligible for colorectal cancer diagnosis and scheduled for a screening colonoscopy. more than 1000 subjects are targeted to enroll.

Individual participant data that underlie the results reported in publications of the study may be shared after de-identification.