Weigl K, Chang-Claude J, Hsu L, et al. - Existing approaches for the estimation of the excess familial risk of cancer that can be attributed to identified common genetic risk variants were examined and using well-established epidemiological methodology, an alternative, more straightforward approach for calculating this proportion was proposed. From a large population-based case–control study in Germany, researchers selected 4,447 cases and 3,480 controls and applied the underlying equations of the traditional approaches and the new epidemiological approach for colorectal cancer (CRC). They observed a 1.77-fold risk increase in correlation to having a family history (FH) of CRC. Based on various assumptions, traditional approaches yielded estimates of the FH-associated risk from 9.6% to 23.1% explained by 97 common genetic variants. Smaller and more consistent estimates of this proportion were attained with the alternative approach, ranging from 5.4% to 14.3%. Results here suggest that familial risk and risk associated with known common genetic variants might represent two complementary major sources of risk.