Fig. 1. Association between the PRS and contralateral breast cancer risk for BRCA1 and BRCA2 heterozygotes.

Effect size of the association between contralateral breast cancer and the three different PRS₃₁₃ after testing for covariates for the following selections: all contralateral breast cancer, invasive contralateral breast cancer only, ER-negative contralateral breast cancer, and ER-positive contralateral breast cancer. The numbers of unilateral and contralateral breast cancer cases and effect sizes are shown in Table 2 and Table S4. CBC contralateral breast cancer, ER estrogen receptor, HR hazard ratio, PRS polygenic risk score, SD standard deviation.