BRCA1 and breast cancer: The only case–control study conducted did not find an elevated risk of breast cancer associated with IVF exposure.18 As women with BRCA1/2 mutations have a high a priori absolute risk of breast cancer development already at early, reproductive ages (cumulative risks of 20% by age 38 and 43 apply for BRCA1 and BRCA2, respectively,1 even a small adverse effect of ovarian stimulation for IVF could have substantial impact.