BRCA1 and breast cancer: Moreover, a study by Milne et al. showed that the use of oral contraceptives for at least 12 months significantly reduced the risk of breast cancer for BRCA1 mutation carriers (OR = 0.22; 95% CI = 0.10–0.49), but not for BRCA2 mutation carriers (OR = 0.93; 95% CI = 0.69–1.24) [115].