The implications of colorectal cancer molecular biology in clinical practice.

Colorectal cancer (CRC) is the third most common malignancy in the United States. Advances in molecular biology have enhanced the understanding of colorectal carcinogenesis. Approximately 75% of CRCs are sporadic; the rest are hereditary or belong to a familial syndrome. Identification of familial forms of CRC have enabled the development of several models of carcinogenesis and made CRC a well-studied malignancy in terms of molecular pathogenesis. Pathways containing multiple mutations and genetic alterations that play a role in hereditary CRC pathogenesis have been elucidated. Many of the molecular changes seen in these pathways also are involved in the development of sporadic cancers.