RecruitingPhase 2Drug trialMolecular Analyses to Predict Pathways of Endocrine Resistance Following Short Term Neoadjuvant Endocrine Treatment in Patients With Hormone Receptor-Positive HER2-negative Breast CancerThis is an exploratory phase II interventional study that initiates standard-of-care anti-estrogen treatment preoperatively for 4-12 weeks (+/- 2 weeks).