Tamoxifen, raloxifene and arzoxifene are recognized as selective estrogen receptor modulators (SERMs), which through their AF2 domain, elicit the effects of ER activation.15 Around 75% of all breast cancers involve hormone receptors, and thus hormonal therapy has revealed a remarkable reduction in reoccurrence of breast cancer and increased the lifespan of patients by 10 years. This evidence concerns the gene ESR1 and breast cancer.