RADT-02. FACTORS ASSOCIATED WITH NEW-ONSET SEIZURES AFTER STEREOTACTIC RADIOSURGERY FOR NEWLY DIAGNOSED BRAIN METASTASES

Abstract

Abstract INTRODUCTION Stereotactic radiosurgery (SRS) is a highly effective therapy for newly diagnosed brain metastases. Risk factors for new-onset seizures after SRS have not been well established. In this study, we aimed to characterize the variables predictive of seizure risk. METHODS Patients treated with SRS for newly diagnosed brain metastases were retrospectively reviewed at a single institution. Data on baseline demographics, radiation parameters, and clinical courses were collected. RESULTS 120 patients without previous seizure history were identified. Median age was 65 years (56-70.8) and baseline KPS 90 (80-90). 16 (13%) patients developed new-onset seizures within 3 months of SRS. In analyses comparing patients with and without new-onset seizures, there was no association between new-onset seizures and baseline KPS(90:80, p=0.48), prior resection (31%:28%, p=0.76), prior WBRT (6%:10%, p=1), immunotherapy or chemotherapy within 1 month (31%:21%, p=0.52 and 56%:57%, p=1), primary tumor site (p=0.07), number of lesions (2.2:3, p=0.21), cerebellar (25%:37%, p=0.41) or brainstem involvement (19%:14%, p=0.71), irradiated maximum target diameter (2.8:2.0cm p=0.191), maximum target volume (7.6:2.9 cm3 p=0.133), total dose of radiation (25:20Gy, p = 0.12), or use of fractionation (56%:35%, p=0.11). However, there was a significant difference in the total irradiated target volume (11.6 vs. 3.8 cm3, p=0.019) and a trend toward increased post-treatment seizures among patients with a total irradiated volume greater than 10cm3 (20%:9%, p=0.11, OR 2.4 [0.85-6.4]). Patients with seizures were also more likely to have received steroids (69%:34%, p=0.012) and AEDs (28%:15%, p=0.021) prior to SRS. CONCLUSIONS Our data suggest that total treatment volume is associated with new-onset seizures within 3 months of SRS. The association between seizures and exposure to steroids or AEDs prior to SRS may be a surrogate for neurologic symptoms at presentation. Patients undergoing SRS to larger volumes and necessitating prophylactic steroids or AEDs may benefit from counseling or intensification of anti-seizure therapy.