REVIEW Colorectal Cancer: Molecules and Populations

The epidemiology and molecular biology of colorectal cancer are reviewed with a view to understanding their interrela-tionship. Risk factors for colorectal neoplasia include a posi-tive family history, meat consumption, smoking, and alcohol consumption. Important inverse associations exist with veg-etables, nonsteroidal anti-inflammatory drugs (NSAIDs), hormone replacement therapy, and physical activity. There are several molecular pathways to colorectal cancer, espe-cially the APC (adenomatous polyposis coli)–b-catenin–Tcf (T-cell factor; a transcriptional activator) pathway and the pathway involving abnormalities of DNA mismatch repair. These are important, both in inherited syndromes (familial adenomatous polyposis [FAP] and hereditary nonpolyposis colorectal cancer [HNPCC], respectively) and in sporadic cancers. Other less well defined pathways exist. Expressio