Genome-wide association studies in cancer.

Genome-wide association studies (GWAS) provide a powerful approach to identify common, low-penetrance disease loci without prior knowledge of location or function. GWAS have been conducted in five of the commonest cancer types: breast, prostate, colorectal and lung, and melanoma, and have identified more than 20 novel disease loci, confirming that susceptibility to these diseases is polygenic. Many of these loci were detected at low power, indicating that many further loci will probably be detected with larger studies. For the most part, the loci were not previously suspected to be related to carcinogenesis, and point to new disease mechanisms. The risks conferred by the susceptibility alleles are low, generally 1.3-fold or less. The combined effects may, however, be sufficiently large to be useful for risk prediction, and targeted screening and prevention, particularly as more loci are identified.