ABSTRACT
BACKGROUND: Treatment strategies for locally advanced breast cancer in elderly patients too frail to receive neoadjuvant chemotherapy and the introduction of new classes of drugs in the early 2000s have led to the consideration of endocrine therapy as a neoadjuvant treatment for younger hormone receptor (HR)-positive, postmenopausal patients not eligible for primary breast-conserving surgery (BCS). METHODS: This was a multicenter, phase 2, randomized trial designed to evaluate as its primary objective the clinical response rate after up to 6 months of neoadjuvant endocrine therapy (NET) alone in HR-positive/human epidermal growth factor receptor 2 (HER2)-negative patients with 1 mg of anastrozole (arm A) or 500 mg of fulvestrant (arm B). Secondary objectives included the BCS rate, tumor response assessment (breast ultrasound and magnetic resonance imaging), pathological response (Sataloff classification), safety profile, relapse-free survival (RFS), and predictive markers of responses and outcomes. RESULTS: From October 2007 to April 2011, 116 women (mean age, 71.6 years) with operable infiltrating breast adenocarcinoma (T2-T4, N0-N3, M0) were randomized to receive anastrozole or fulvestrant. The clinical response rates at 6 months were 52.6% (95% confidence interval [CI], 41%-64%) in arm A and 36.8% (95% CI, 25%-49%) in arm B. BCS was performed for 57.6% of arm A patients and 50% of arm B patients. The RFS rates at 3 years were 94.9% in arm A and 91.2% in arm B. The Preoperative Endocrine Prognostic Index status was significantly predictive of RFS. Both treatments were well tolerated. CONCLUSIONS: Both drugs are effective and well tolerated as NET in postmenopausal women with HR-positive/HER2-negative breast cancer. NET could be considered a treatment option in this subpopulation. Cancer 2016;122:3032-3040. © 2016 American Cancer Society.