Screening high-risk populations for colon and rectal cancers.

Currently, colorectal cancers accounted for the second-highest number of cancer deaths in the US. Hereditary syndromes, strong family history, and inflammatory bowel disease are all conditions that confer predisposition risks. In hereditary syndromes, screening must be more frequent and start earlier. With familial risk, screening should depend on the age of cancer onset and number of affected relatives. For inflammatory bowel disease, surveillance should depend on duration, severity, and extent of colitis.