Results from the Suppression of Ovarian Function Trial (SOFT) and Tamoxifen and Exemestane Trial (TEXT) trials, and subsequently the Addition of Ovarian Suppression to Tamoxifen in Young Women With Hormone-Sensitive Breast Cancer Who Remain Premenopausal or Regain Vaginal Bleeding After Chemotherapy (ASTRRA) trial, have indicated that the addition of ovarian function suppression to tamoxifen or an aromatase inhibitor (AI) improves disease-free survival, freedom from distant recurrence, and overall survival11–13. This evidence concerns the gene CYP19A1 and breast cancer.