Genome-Wide Association Studies and Colorectal Cancer

Genome-wide association studies (GWAS) provide a powerful new approach to identify common, low-penetrance susceptibility loci without prior knowledge of biologic function. Results from three GWAS conducted in populations of European ancestry are available for colorectal cancer (CRC). These studies have identified 11 disease loci that, for the majority, were not previously suspected to be related to CRC. The proportions of the familial and population risks explained by these loci are small and they currently are not useful for risk prediction. However, the power of these studies was low, indicating that a number of other loci may be identified in new ongoing GWAS, and in pooled analyses. Thus, the risk prediction ability of susceptibility markers identified in GWAS for CRC may improve as more variants are discovered. This may, in turn, have important implications for targeting high-risk individuals for colonoscopy screening.