which breast cancer screening should start and the screening interval. In the UK, mammogram screening is offered to women over age 47, when the average 10-year risk of breast cancer is ~ 2.6%. However, Mavaddat et al. [3] show that PRS is informative in stratifying risk, with the 20% of women with the highest polygenic risk scores reaching this level of risk before age 40 and the 20% of women with the lowest scores never reaching this level of risk. This study shows that breast cancer polygenic risk scores already capture sufficient information to identify a high-risk subgroup of women who could be offered mammogram screening at an earlier age. Commercial breast cancer risk tests based on polygenic risk scores are already offered by Myriad Genetics (riskScore™) and Ambry Genetics (AmbryScore).
