RADT-73. IMPACT OF AGE-RELATED AND CLINICAL RISK FACTORS ON SURVIVAL IN TRIPLE NEGATIVE BREAST CANCER PATIENTS WITH BRAIN METASTASES TREATED WITH STEREOTACTIC RADIOSURGERY

Abstract BACKGROUND Triple-negative breast cancer (TNBC) carries a high risk of brain metastases and poor prognosis. The impact of estrogen-related factors, such as age at breast cancer diagnosis, on survival in this setting remains underexplored. Clinical variables, including extracranial disease and comorbidities, may also influence outcomes after stereotactic radiosurgery (SRS). OBJECTIVE To assess whether age at breast cancer diagnosis and other clinical factors are associated with overall survival (OS) and post-brain metastasis survival (BM-OS) in TNBC patients treated with SRS. METHODS We retrospectively analyzed 24 TNBC patients who underwent SRS for brain metastases at our institution. Variables included age at breast cancer diagnosis, age at brain metastasis diagnosis, extracranial metastasis status, comorbidity burden, number of brain metastases, and brain metastasis-free interval (BMFI). The optimal age cutoff (52 years) was identified using the Youden index. Kaplan-Meier and multivariable Cox proportional hazards analyses were performed to evaluate associations with OS and BM-OS. RESULTS Patients diagnosed with breast cancer before age 52 had significantly longer OS compared to those diagnosed at ≥52 years (p < 0.05). On multivariable analysis, younger age (<52 years) remained an independent predictor of improved OS after adjusting for extracranial metastases and race (hazard ratio 2.62, p < 0.05). Higher comorbidity burden and presence of extracranial metastases were not associated with worse BM-OS. BMFI did not significantly predict OS or BM-OS. CONCLUSIONS Age at TNBC diagnosis <52 years, potentially reflecting estrogen-related factors, independently predicts improved OS in patients with brain metastases treated with SRS. These findings may aid risk stratification and inform treatment planning in this high-risk population.