This secondary pooled analysis of randomized phase II prospective studies re-examines the use of neoadjuvant endocrine therapy among a cohort of premenopausal and postmenopausal patients with early-stage HR + , human epidermal growth factor receptor 2-negative (HER2-) breast cancer randomized to neoadjuvant endocrine therapy or neoadjuvant chemotherapy based on Oncotype DX® assay performed on initial core biopsy specimens. The gene discussed is ERBB2; the disease is breast carcinoma.