Treatment and outcomes of older versus younger women with HER2 positive metastatic breast cancer in the real-world national ESME database

Background: Treatment and outcomes of patients with HER2-positive (HER2+) metastatic breast cancer (MBC) have dramatically improved over the past 20 years. This work evaluated treatment patterns and outcomes according to age. Methods: Women who initiated a treatment for HER2+ MBC between 2008 and 2016 in one of the 18 French comprehensive centers part of the ESME program were included. Objectives were the description of first-line treatment patterns, overall survival (OS), first-line progression-free survival (PFS), and prognostic factors among patients aged 70 years or more (70+), or less than 70 (<70). Results: Of 4045 women diagnosed with an HER2+ MBC, 814 (20%) were 70+. Standard first-line treatment (chemotherapy combined with an anti-HER2 therapy) was prescribed in 65% of 70+ versus 89% of <70 patients (p < 0.01). Median OS was 49.2 (95% CI, 47.1-52.4), 35.3 (95% CI, 31.5-37.0) and 54.2 months (95% CI, 50.8-55.7) in the whole population, in patients 70+ and <70, respectively. Corre-sponding median PFS1 were 12.8 (95% CI, 12.3-13.3), 11.1 (95% CI, 10.0-12.3) and 13.2 months (95% CI, 12.7-13.9), respectively. In 70+ women, initiation of non-standard first-line treatment had an inde-pendent detrimental time-varying effect on both OS and PFS (HR on OS at 1 year: chemotherapy without anti-HER2 2.79 [95% CI: 2.05-3.79]; endocrine therapy and/or anti-HER2 1.96 [95% CI: 1.43-2.69]). Conclusions: In this large retrospective real-life database, older women with HER2+ MBC received standard first-line treatment less frequently than younger ones. This was independently associated with a worse outcome, but confounding factors and usual selection biases cannot be ruled out. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).