For HR+/HER2– metastatic breast cancer (mBC), international guidelines recommend the use of endocrine therapy (ET) as first-line (L1) treatment except in case of “visceral crisis” for which chemotherapy (CT) is advised. Few studies directly compare these two treatment options. In 2014, UNICANCER launched the Epidemiological Strategy and Medical Economics (ESME) Research program to centralize real-world data in oncology. We sought to use this database to study this question.
All patients (pts) who initiated treatment for a newly diagnosed mBC between January 2008 and December 2014 in all 18 French Comprehensive Cancer Centers were included in the ESME mBC database. ESME Research program centralized all existing data using retrospective data collection. Primary endpoint of the present study was progression free survival (PFS1) and overall survival (OS) according to L1 treatment for aromatase inhibitors sensitive (AIS) HR+/HER2- mBC pts.
6265 pts out of 16703 in ESME, had AIS HR+/HER2- mBC. As L1 therapy, 2733 pts (43.6%) received ET alone, while 3532 received CT (56.4%). Among these 3532 pts, 2073 (58.7%) received ET as maintenance treatment after CT. A Cox multivariate analysis with significant prognostic variables identified a lower risk of death in the patients with L1 ET (HR = 0.839, 95% IC [0.772-0.911], p
The results show that despite guidelines, a majority of AIS HR+/HER2- mBC pts still received CT as first-line treatment in the past years. PFS1 and OS data do not suggest any advantage of this aggressive strategy over ET alone. Advanced statistical methods using the propensity score will be presented in order to control for potential selection bias.
Clinical trial identification
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All authors have declared no conflicts of interest.