Abstract P1-03-05: Overview of the management and factors associated with outcomes of metastatic breast cancer among elderly patients
Authors: Mendes Sofia Vidaurre , Orsi Bruna Zanin , Vasconcellos Jessica Monteiro , Neto Augusto Araujo , Rocha Erika Andrade , Messias Ana Paula , Moreira Otavio Noschang , Freire Pedro José Galvão , Leis Leticia Vecchi , Pereira Mauricio Baptista , Petry Vanessa , Bonadio Renata Colombo , Testa Laura 
Published: March 2023

Background: Management of metastatic breast cancer (mBC) in elderly patients (pts) faces some challenges since some pts are frail or have functionality impairment, with higher risk of severe adverse events from oncologic therapy. We aimed to assess the treatment patterns for elderly pts with MBC and evaluate factors associated with outcomes in this population. Methods: This retrospective study evaluated pts 70 years and older with mBC treated in a tertiary cancer center from 2009 to 2022. Charlson index (ChI) was used to measure comorbidities. Endpoints were proportion and type of first-line systemic therapy, rates of treatment discontinuation due to toxicities, overall survival (OS) and prognostic factors. The Kaplan-Meier method was used for survival analyses. Hazard ratio (HR) and 95% confidence interval (95% CI) were calculated using Cox regression. Results: 460 pts with mBC were evaluated. Median age was 78 years (IQR 70-96). Most pts (n=331; 72%) had hormone receptor-positive HER2-negative (HR+HER2-) BC, while 11% (n=50) had HER2-positive (HER2+) BC and 14% (n=64) triple-negative (TN) BC. Most pts has de novo metastatic disease (n=316; 69%); ECOG-PS 3-4 (n=313, 68%), and ChI ≤ 7 (n=354; 77%). Forty-five pts (10%) did not receive systemic therapy for metastatic BC; this proportion was higher among TNBC (34%) than other subtypes (HR+HER2-: 5%; HER2+: 6%) (P&lt; 0.001). The proportion not receiving systemic therapy was also higher among pts with ECOG-PS 3-4 (13%, P&lt; 0.001), older than 90 years (19%; P=0.069), and with ChI &gt; 7 (15%; P=0.088). Among 165 pts who received first-line endocrine therapy, 2% discontinued due to toxicity. Ninety pts received first-line chemotherapy and 18% discontinued due to toxicity. Breast cancer was the main cause of death (94%) in the cohort. Factors associated with increased risk of death were HER2+BC (HR 1.48, 95% CI 1.04 – 2.09; P=0.027), TNBC (HR 1.52, 95% CI 1.05 – 2.20; P=0.025), age group 80-90 years (HR 1.30, 95% CI 1.02-1.64; P=0.028), ECOG-PS 3-4 (HR 2.34, 95% CI 1.73-3.15, P&lt; 0.001), and not receiving systemic therapy (HR 4.48, 95% CI 2.88-6.98, P&lt; 0.001). Median OS was 29 months for pts treated with systemic therapy, and 2.3 months for those who did not receive it (P&lt; 0.001). Conclusions: Many factors influence the prognosis and the treatment decision for elderly pts with mBC. The rates of pts who do not receive systemic therapy are higher among TNBC, which points to the need for better tolerated therapies for this group.

Citation Format: Sofia Vidaurre Mendes, Bruna Zanin Orsi, Jessica Monteiro Vasconcellos, Augusto Araujo Neto, Erika Andrade Rocha, Ana Paula Messias, Otavio Noschang Moreira, Pedro José Galvão Freire, Leticia Vecchi Leis, Mauricio Baptista Pereira, Vanessa Petry, Renata Colombo Bonadio, Laura Testa. Overview of the management and factors associated with outcomes of metastatic breast cancer among elderly patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-03-05.