ESR1 and invasive breast carcinoma: In this phase III randomized clinical trial, postmenopausal women with a cT2–4 N0-3 M0 ER+ HER2- invasive breast cancer were randomized to (I) neoadjuvant anastrozole followed by surgery, and then anastrozole for 4.5 years; (II) neoadjuvant fulvestrant, surgery, followed by fulvestrant for the first 18 months and anastrozole for 3 years; and (III) the combination of anastrozole and fulvestrant.