BRCA1 and breast cancer: This is all the more important given the high prevalence of heterozygous BRCA1/2 germline mutations (i.e., 1:400 up to 1:200 persons in some general populations19 and 1:40 in certain ethnic groups.20 The aim of the current study is to evaluate whether exposure to ovarian stimulation for IVF increases the risk of primary breast cancer in BRCA1 and BRCA2 mutation carriers.