Early detecting and removing of colorectal advanced adenomas can reduce the incidence of colorectal cancer. Because of the less bleeding of advanced adenomas, sensitivities of the common used quantitative fecal immunochemical tests (qFITs) are unsatisfying. Ultra-sensitivity qFIT(us-qFIT) can determine extremely low fecal hemoglobin concentration compared with the common used qFIT. This study will prove the diagnostic accuracy of us-qFIT in detecting colorectal advanced adenomas.

Early detection of CRC in a curable stage can reduce mortality but not morbidity. The majority of colorectal cancer is thought to arise from precancerous lesions through the adenoma-carcinoma pathway. Detecting and removing of colorectal advanced adenomas can reduce incidence of colorectal cancer. Although colonoscopy is currently considered the most effective method for detecting advanced adenomas, individuals may be reluctant to undergo colonoscopy due to the uncomfortable feeling and the relatively high cost. Conversely, stool tests are relatively cheap and more readily accepted. Fecal immunochemical test (FIT) is economic and easy to use in colorectal cancer screening. However, the common used qFIT is insufficiently sensitive to the minor hemorrhage of advanced adenomas, and the sensitivity is about only 27% to 47%. To improve the detection rate of colorectal advanced adenoma, Ultra-sensitivity quantitative fecal immunochemical test (us-qFIT) improves technology and can detect fecal hemoglobin in extremely low concentration quantificationally. The investigators design this research to prove the diagnostic accuracy of us-qFIT in detecting colorectal advanced adenoma.

Inclusion Criteria:

• 50-75 years old people;
• People sign an "informed consent form"

Exclusion Criteria:

• People with history of colorectal surgery;
• People with history of colorectal cancer;
• People with history of other diseases that may produce fecal blood, such as inflammatory bowel disease, ischemic enteritis, vascular alformation of intestine, intestinal tuberculosis or Non-Hodgkin's lymphoma involving digestive tract;
• People with symptoms including visible rectal bleeding, hematuria, hemorrhoid bleeds, severe and acute diarrhea and watery stool;
• People are in pregnancy, lactation or menstrual phase;
• People with severe congestive heart failure or other sever disease cause cannot tolerate colonoscopy.

Continuous participants intending to undergo colonoscopy and meet the inclusion and exclusion criteria from the 5 hospitals were enrolled.