Progress and challenges in colorectal cancer screening and surveillance.

Colorectal cancer is a leading cause of cancer death throughout the world. There is evidence that screening of average-risk individuals can result in mortality reduction with early cancer detection and cancer prevention by detection and removal of cancer precursor lesions. The optimal form of screening is not clear. Fecal screening tests can be performed at home at low initial cost, but current versions lack high sensitivity for cancer precursor lesions, and tests need to be repeated at regular intervals. Adherence to repeat testing for negative tests and referral for colonoscopy for positive tests are important elements of program effectiveness. Structural examinations of the colon are more invasive and may result in detection of both early cancer and cancer precursor lesions. Every screening program has advantages and limitations, but each program ultimately depends on quality and patient adherence.