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e13111 Background: Brain metastasis (BM) contributes to substantial morbidity and mortality for breast cancer (BCa) patients (pts). Advances in systemic therapies have improved survival following BM diagnosis; however, other factors such as age, timing of BM development, and molecular features may also affect outcomes. Here we characterize the overall survival (OS) of pts with BM secondary to BCa treated at our institution with the aim of identifying predictors that can used to improve treatment and management. Methods: In an electronic medical record of “brain metastasis” and “breast cancer”, we identified pts aged >18 years treated between 2015 and 2022. All cases were manually reviewed by ≥2 reviewers. Cases with second metastatic (met) solid tumors, hematologic malignancies, or insufficient data were excluded. Only cases with intraparenchymal and/or leptomeningeal disease attributed to met BCa were included. Kaplan-Meier estimation and Cox regression were applied to OS. Results: Of 344 cases reviewed, 229 (1 male) were appropriate for inclusion. The median age at BM diagnosis (dx) was 58 years. 28% underwent surgical resection and 81% received radiation treatment for BM. With a median follow-up of 5 years, 82% of pts died and median OS (mOS) following BM dx was 14 months (95% CI: 9-19). Among 208 pts without de novo BM, time to BM development (mTBM) from primary BCa varied by subtype: mTBM (IQR) HR+HER2- of 6.4 years (3.9-10.5), HR+HER2+ of 3.5 years (2.0-9.1), HR-HER2+ of 2.1 years (1.2-3.1), TNBC of 2.4 years (1.1-4.9). mOS varied by BCa subtype (table, log-rank p=0.029). 41 cases had de novo met disease (met dx ≤2 months of BCa dx) with 21 (9%) having de novo BM. HER2+ BCa and shorter mTBM were associated with longer mOS (table). Pts with BM dx in 2 nd or later met relapse vs. earlier BM (de novo or 1 st met relapse), OS HR was 1.67 (95% CI: 1.24-2.25; p=0.001). OS did not vary by age at BM diagnosis. Conclusions: Our findings build on prior work showing differential BM survival by subtype. We observe significantly shorter post-BM survival among pts who develop BM after a second or later line of met treatment. Ongoing work will expand our database and explore molecular features of resected brain tumors. Table: see text
Chun et al. (Sat,) studied this question.