The primary objective is to determine the sensitivity and specificity of two Colorectal Cancer (CRC) screening methods, including stool DNA test and blood mRNA test, for colorectal cancer in Chinese population, with colonoscopy as reference method. Lesions will be confirmed as malignant or precancerous by colonoscopy and histopathologic examination.

The secondary objective is to compare the performance of these two CRC screening methods to a commercially available FIT assay, both with respect to cancer and advanced adenoma. Lesions will be confirmed as malignant or precancerous by colonoscopy and histopathologic examination.

Participants who are at high risk of developing colorectal cancer will be asked to collect two stool samples one for the stool DNA test and the other for the commercially available FIT assay, and a single blood sample for the blood mRNA test. Subjects will undergo colonoscopy within 6 months of enrollment. Representative histopathology slides from tissue biopsied or excised during colonoscopy and those from subsequent definitive surgery may be retrieved in order to be evaluated by pathologists to confirm the diagnosis and staging.

Inclusion Criteria:

1. Subjects received screening questionnaire and had been defined as high risk.
2. Subjects haven't received any treatment under colonoscopy within 10 years.

Exclusion Criteria:

1. Subjects are under the usage of specific drugs which might affect the screening test.
2. Subjects had the contraindication for colonoscopy.

Participants at high risk of developing colorectal cancer.