Abstract P1-07-34: Clinical outcomes of single versus double hormone receptor positive breast cancer patients treated with neoadjuvant chemotherapy

Abstract

Abstract Purpose 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 Methods 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 Results Three hundred and four BC patients were identified and included in the analysis with a median follow up of 43.3months (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 <0.0001). In a MLR analysis, HR status and HER2 status were associated with pCR rates. Compared to HR negative patients, patients with double HR+ disease were less likely to achieve pCR (Odd ratio (OR):0.14, 95%CI 0.06-0.31, p<0.0001) while single HR+ patients did not differ (OR:0.51, 95%CI 0.19-1.4). The association between HR+ status (single versus double HR+) and pCR rates compared to HR negative patients remained the same in subgroup analyses of HER2+ and HER2 negative patients separately. No difference in survival (DFS) was seen between the 3 subgroups of patients: HR negative, single and double HR+ patients. Conclusion 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. Citation Format: Raphael J, Nofech-Mozes S, Trudeau ME. Clinical outcomes of single versus double hormone receptor positive breast cancer patients treated with neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-07-34.