Efficacy of neoadjuvant endocrine therapy compared with neoadjuvant chemotherapy in pre-menopausal patients with oestrogen receptor-positive and HER2-negative, lymph node-positive breast cancer

Introduction: Neoadjuvant endocrine therapy (NET) has demonstrated efficacy in post-menopausal patients with hormone-responsive breast cancer. This trial was designed to compare the efficacy of neoadjuvant chemotherapy (NCT) with NET in pre-menopausal breast cancer. Patients and methods: In this prospective, randomised, phase III study, oestrogen receptor (ER)-positive, HER2-negative, and lymph node-positive pre-menopausal breast cancer patients were recruited from 7 hospitals in South Korea. Enrolled patients were randomly assigned (1:1) to receive 24 weeks of either NCT or NET with goserelin and tamoxifen. The primary purpose was to evaluate the non-inferiority of NET compared to NCT using clinical response, assessed by MRI. Besides, pathological complete response rate (pCR), changes in Ki-67 expression, breast conservation surgery (BCS) rate, and quality of life were included as secondary endpoints. Results: A total of 187 patients were assigned to receive NCT (n = 95) or NET (n = 92), and 87 patients in each group completed treatments. More NCT patients had complete response or partial response than NET patients using MRI (NCT 83.7% vs. NET 52.9%, 95% CI 17.6-44.0, p < 0.001) and callipers (NCT 83.9% vs. NET 71.3%, 95% CI 0.4-24.9, p = 0.046). Three NCT patients (3.4%) and one NET patient (1.2%) showed pCR (p < 0.005). No difference existed in the conversion rate of BCS (13.8% for NCT vs. 11.5% for NET, p = 0.531) and Ki-67 change (p = 0.114) between the two groups. Nineteen NCT patients had treatment-related grade 3 or worse events compared with none in the NET group. Conclusions: Better clinical responses were observed in pre-menopausal patients after 24 weeks of NCT compared to those observed after NET. Trial registration: Clinicaltrials.gov, NCT01622361. Registration June 19, 2012.