Potent ais8,9 were developed for complete estrogen blockade in postmenopausal women (by inhibiting the cytochrome P450 aromatase complex that converts peripheral androgens to estradiol), and compared with tamoxifen, they have demonstrated greater efficacy and a favourable side effect profile in both early- and late-stage hormone receptor–positive breast cancer 10–12. This evidence concerns the gene NR4A1 and breast carcinoma.