Background: Breast cancer (BC) is the second most common etiology of brain metastases (BrM). We aimed to examine the incidence of BrM among all BC patients presenting to a large tertiary cancer centre over one decade.
Methods: We included all BC patients presenting consecutively between 2009 and 2019 and cross referenced that cohort to a radiotherapy database, identifying patients treated for BrM at any time following their initial presentation. Cumulative incidences (CI) of BrM diagnoses were calculated using death as a competing risk and compared using the Fine-Gray method. Overall survival was estimated using the Kaplan Meier method.
Results: We identified 12,995 unique patients. The CI of BrM in patients who initially presented with Stage 0-4 disease was 2.1%, 3.7%, 9.4%, 10.6%, and 28.7%, respectively at 10 years. For 8,951 patients with available molecular subtype data, 6,470 (72%), 961 (11%), 1,023 (11%), and 497 (6%) had hormone-receptor (HR)-positive/ERBB2-, HR-negative/ERBB2-, HR-positive/ERBB2 + , and HR-negative/ERBB2 + disease, respectively; the CI of BrM in each was 7.6%, 25.3%, 24.1%, and 26.6%, at 10 years following BC diagnosis, respectively. Median overall survival (OS) following BC diagnosis and BrM diagnosis was 28 years 95% CI [25, 32] and 10 months 95% CI [9, 12], respectively.
Conclusions: From a large, registry-based study, we observed that patients with ERBB2 + and triple negative BC have the highest incidence of BrM. Our data supports prospective surveillance brain MRI studies. Given advancements in BrM treatment, clinicians should have a low threshold for brain imaging in BC patients with high risk subtypes.
Keywords: Brain metastases; Breast cancer; ERBB2 +; HER2 +; Molecular subtype; Trastuzumab; Triple negative.
© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.