Patterns of presentation, treatment, and survival among older adults with metastatic breast cancer: Results from a large prospective registry.

introductionOlder adults with breast cancer experience worse survival than their younger counterparts. However, data are limited on the patterns of presentation, treatment, and outcomes for older patients with metastatic breast cancer (MBC) outside of registry studies and selected clinical trial populations. MATERIALS AND

methodsWe identified patients aged ≥60 years from a single, NCI-designated cancer center with MBC diagnosed between 1999 and 2022. Using Chi-square testing, we compared clinicopathologic characteristics by age. We also examined treatment patterns and reasons for treatment discontinuation; overall survival (OS) was examined by subtype and age using Kaplan-Meier methods.

resultsThe final analytic cohort included 1115 patients with a median follow-up of 2.9 years (1.0-18.5); median age at metastatic diagnosis was 66.3 (60.0-95.4). Disease subtypes included: 70.7 % hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-), 11.9 % any HR/HER2+, 17.4 % triple negative (TN). In those with HR+/HER2- disease receiving first-line (1 L) therapy (n = 783), 1 L endocrine-based therapy was frequent (79.3 % for ages 60-65, 94.7 % for >80), and administration of 1 L chemotherapy varied by age (21.0 % in ages 60-65, 5.3 % in >80). Among those with TN and HER2+ disease, ≥84 % received a 1 L chemotherapy or trastuzumab-containing regimen. Across subtypes, most patients (80.5 %) discontinued 1 L therapy for progression, not toxicity. Among patients ages 60-65, 16.5 % stopped treatment after 1 L therapy; 42.2 % of those >age 80 received treatment after 1 L. Clinical trial enrollment declined with age (40 % in 60-65 vs. 13 % for >80; p = 0.0004), as did median OS (4.4 years in ages 60-65 vs. 2.7 years for >80; p < 0.005). For ages 60-65, 37.8 %, 17.1 %, and 40.3 % with HR + HER2-, TN, and HER2+ disease, respectively, were alive at two years. For ages >80, 23.7 %, 0 %, and 33.3 % with HR + HER2-, TN, and HER2+ disease, respectively, were alive at two years. DISCUSSION: In a unique, large prospective cohort of older adults with MBC, the number of treatment lines decreased with increasing age, and OS outcomes were poor, particularly for those >80 years where most patients were not alive at two years after MBC diagnosis. Therapeutic approaches, with improved supportive care, are urgently needed to optimize outcomes in the oldest patients with MBC.