RADT-01. PROGNOSTIC FACTORS FOR 90-DAY SURVIVAL AFTER STEREOTACTIC RADIOSURGERY FOR BRAIN METASTASIS PATIENTS

Abstract Brain metastases significantly impact neurocognitive function and overall survival. Stereotactic radiosurgery (SRS) is a cornerstone of treatment for patients with limited metastases and expected survival beyond three months. Despite current guidelines, up to 20% of patients with brain metastases undergoing SRS have been reported to die within 90 days. This study retrospectively evaluates prognostic factors associated with 90-day survival after SRS, aiming to improve patient selection. We retrospectively analyzed a cohort of 1,546 patients who underwent Gamma Knife SRS for brain metastases at our institution between 2015 and 2023. One hundred seventy patients who survived fewer than 90 days post-SRS were identified and case-matched to 170 patients who survived over 90 days. Measured variables included patient demographics, tumor characteristics, treatment history, functional status, and control of the primary cancer. We modeled post-SRS 90-day survival using binomial and multivariate logistic regression. Multivariate analysis highlighted Karnofsky Performance Status (KPS) < 70 (OR: 17.4, p < 0.001), prior whole brain radiation (OR: 6, p = 0.004), and focal neurological deficits (OR: 3.02, p = 0.003) as significant predictors of early deaths, while CNS progression before SRS (OR: 0.22, p < 0.001) and control of systemic cancer (OR: 0.556, p = 0.002) were associated with a less than 90-day survival. The predictive model demonstrated acceptable performance with an area under the curve (AUC) of 0.85, accuracy of 80%, sensitivity of 87%, and specificity of 71%. Key predictors of 90-day survival following SRS for brain metastases include functional status (KPS), control of systemic cancer, CNS progression status, and focal neurologic deficits. These findings are complementary factors that can assist in making decisions and SRS patient selection.