Clinical Outcomes of Single Versus Double Hormone Receptor–Positive Breast Cancer Patients Treated With Neoadjuvant Chemotherapy

Abstract

PurposeTo compare tumor response rates and survival outcomes between single and double hormone receptor (HR)-positive breast cancer (BC) patients treated with neoadjuvant chemotherapy. Patients and MethodsA retrospective review was conducted using the Sunnybrook Biomatrix database to identify eligible patients. A multivariable logistic regression analysis was performed to assess the association between HR status (single/double HR+) and pathologic complete response (pCR) rates. A Kaplan-Meier method was used to estimate recurrence-free survival (RFS), and a log-rank test was used to compare RFS between 3 subgroups: single or double HR+ and HR− patients. ResultsThree hundred four BC patients were included in the analysis with a median follow-up of 43.3 months (Q1-Q3, 28.7-61.1). Forty-seven percent (47/101), 31% (11/36), and 14% (23/167) of patients with HR−, single HR+, and double HR+ disease experienced pCR, respectively. Patients’ characteristics differed between single and double HR+ disease (age, human epidermal growth factor receptor 2, and nodal status). Only in univariate analysis were patients with single HR+ disease more likely than patients with double HR+ disease to experience a pCR (odds ratio = 2.6; 95% confidence interval, 1.14-6.01; P = .02). However, this association did not remain significant in multivariable logistic regression analysis (odds ratio = 1.82; 95% confidence interval, 0.72-4.56; P = .2). No difference in survival (RFS) was seen in the 3 subgroups: HR−, and single and double HR+ patients. ConclusionPatients with single versus double HR+ BC have different tumor characteristics. Their outcome may differ in terms of pCR and survival. Prospective studies are needed to validate this conclusion, which may have treatment implications.