BRCA1 and breast cancer: This may account for the fact that, although parity and oral contraceptive use are strongly protective against extra-uterine Müllerian carcinomas even in BRCA1 mutation carriers [5,16,17,18,19], oral contraceptives appear to increase risk of at least certain subtypes of breast cancer in at least certain segments of the general population, while their effect on breast cancer risk in BRCA1 mutation carriers is unclear [7,8,20,21].