This study aimed to evaluate and compare tumor response rates and survival outcomes between single and double hormone receptor (HR) positive (+) [Estrogen Receptor (ER+)/Progesterone Receptor (PR) negative (-) or ER-/PR+ versus ER+/PR+] breast cancer (BC) patients with any HER2 status treated with neoadjuvant chemotherapy at a single institution.
A retrospective review was conducted using the Sunnybrook “Biomatrix” database to identify eligible patients. A multivariable logistic regression analysis (MLR) was performed to assess the association between HR status (single or double HR+) and pathologic complete response (pCR) rates at surgery. A Kaplan-Meier method was used to estimate Disease Free Survival (DFS) and a log-rank test was used to compare DFS between 3 subgroups of patients: single or double HR+ and HR negative patients.
Three hundred and four BC patients were identified and included in the analysis with a median follow up of 43.3 months (Q1-Q3: 28.7-61.1) and a mean age of 49.7 years (Standard deviation 10.9). Forty seven percent (47/101), 31% (11/36) and 14% (24/167) of patients with HR negative, single HR+ and double HR+ disease achieved a pCR respectively (X2 test
BC patients with single HR+ disease behave differently than double HR+ patients in terms of likelihood of achieving pCR after neoadjuvant chemotherapy and do not differ from HR negative patients. This difference does not translate into a difference in DFS. Prospective studies are needed to validate these findings before considering different treatment strategies for these 2 subgroups of HR+ BC patients.
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All authors have declared no conflicts of interest.