BRCA1 and breast cancer: Kotsopoulos et al. did not find an increased risk for breast cancer in BRCA1 P/LPV carriers treated with HRT, but in those taking combined (estrogen plus progesterone) HRT, the 10-year actuarial risk of breast cancer was 22%, as compared with 12% in those taking estrogen alone, with no statistically significant differences based on age [117].