ESR1 and breast cancer: This is the risk estimate utilized for the major breast cancer prevention trials and supported by NCCN guidelines.21 Based on risk–benefit tables developed by Freedman et al.29 the USPSTF concludes that, in general, women with an estimated 5-year breast cancer risk of ≥3 % are likely to have more benefit than harm from using a selective estrogen receptor modulator (SERM) as chemoprevention, although the balance depends on age, ethnicity, the medication used, and whether or not the patient has a uterus.23