Abstract P6-13-07: Chemotherapy with and without trastuzumab or no treatment in elderly patients with HER2 amplified breast cancer at a single center
Authors: S Muhsen, C Dang, G Plitas, K Seier, M Stempel, S Patil, M Morrow, M El-Tamer
Journal: Cancer Research (2018)

Abstract Introduction Trastuzumab with systemic chemotherapy has shown an improvement in outcomes for patients (pts) with HER2 amplified/overexpressed (HER2+) breast cancer. Pts enrolled onto trials were young with a minority of pts at ≥65 years (yrs) of age. Herein, we report the administration of systemic treatment (ST) (chemotherapy and/or trastuzumab) verus no treatment in elderly pts at a single center. Methods Patients ≥65 yrs with stage I-III HER2+ (defined as IHC 3+ or FISH &amp;gt;2.0) breast cancer, treated at Memorial Sloan Kettering Cancer Center between 2000-2012, were retrospectively identified from our database. Clinicopathologic features were retrieved and co-morbidity indexes (CI) were calculated. Pts were divided by hormone receptor (HR) (defined as ER &amp;gt;10% and/or PR &amp;gt;10%) status into HER2+HR- and HER2+HR+. Each group was further divided by use of ST into: chemotherapy and trastuzumab (CT+T), chemotherapy alone (CT) or no systemic treatment (No Rx). Patients receiving neoadjuvant ST or trastuzumab only as ST were excluded from the KM analysis. Primary objective was to identify patterns of treatment recommendation in the elderly population. We explored disease-free survival (DFS) as estimated using the Kaplan-Meier (KM) method. Results We identified 300 pts ≥65 yrs with HER2+ tumors. 128 (42.7%) were HER2+HR- and 172 (57.3%) were HER2+HR+. The median follow-up for all patients was 6.1 years (range, 0.07-16.7). In the HER2+HR- group, 63 (49.2%) patients received CT+T, 25 (19.5%) CT alone, and 40 (31.3%) had no Rx. Anthracycline based chemotherapy was administered to 57/88 (65%) of patients on CT. Women receiving chemotherapy with or without trastuzumab were younger (65-70 vs &amp;gt;70 years of age) (p=.002) and had more advanced tumor stages (p=.003). Their respective 5-yr DFS KM estimates were 0.84, 0.80, and 0.61 (logrank p=0.06). In the HER2+HR+ group, 77 (44.8%) patients received CT+T, 22 (12.8%) CT alone, and 73 (42.2%) had no Rx. Anthracycline based chemotherapy was administered to 51/99 (51%) of patients on CT. Endocrine therapy was given to 153/172 (89%) of the total cohort. Women receiving chemotherapy with or without trastuzumab were younger (p&amp;lt;.001), and had higher nuclear grade (NG) (p=.04), more lymphovascular invasion (&amp;lt;.001) and more advanced tumor stages (p=.002). Their respective 5-yr DFS KM estimates were 0.84, 1.00, and 0.83 (log rank p=0.02). Conclusions At a single center, in the elderly populations at ≥65 years of age with HER2+ HR- and HER2+HR+ breast cancer, pts who received systemic treatment were younger and had higher stage of disease than those who received no treatment. In an exploratory analysis, there appeared to be a benefit of systemic treatment in pts in the HER+HR- group. Citation Format: Muhsen S, Dang C, Plitas G, Seier K, Stempel M, Patil S, Morrow M, El-Tamer M. Chemotherapy with and without trastuzumab or no treatment in elderly patients with HER2 amplified breast cancer at a single center [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 P6-13-07.