BRCA1 and breast cancer: The weighted average lifetime BC risk is approximately 60% for BRCA1/BRCA2 PV carriers61 and approximately 41.8% for other women with increased risk.62 Given the lifetime risk of approximately 11% in the general population, the proportion of BC cases from women with a 35% or higher lifetime BC risk is calculated with the following equation: (60% × 0.5% + 41.8% × 2.5%)/11% = 12.23%.