PGR and breast cancer: The preoperative anastrozole compared with tamoxifen (PROACT) trial was a randomised, multicentre, double-blind study comparing three months of anastrozole to tamoxifen as preoperative treatment of postmenopausal women with large, operable (T2/3, N0-2, M0), or potentially operable (T4b, N0-2, M0) ER+ and/or PgR+ invasive BC [26].