489 Risk of Intra-Tumoral Hemorrhage (ITH) in Patients With Brain Metastases Treated With Stereotactic Radiosurgery (SRS)

INTRODUCTION: Complications related to intracranial intra-tumoral hemorrhage (ITH) in patients treated with SRS are rare and often require only expectant management. However, there is uncertainty whether anticoagulation therapy (ACT) or antiplatelet therapy (APT) might increase the risk of ITH in brain metastases (BM) treated with Stereotactic Radiosurgery (SRS). METHODS: We evaluated 266 consecutive patients (1169 BMs) treated with SRS from January 1, 2020, to December 31, 2021(Retrospective review, IRB approved). Magnetic Resonance Imaging (MRI), including T1-weighted and microhemorrhage-sensitive susceptibility-weighted imaging (SWI) and gradient-recalled echo (GRE) sequences performed pre-procedure and at first follow-up were evaluated for hemorrhage by a single neuro-radiologist (TE). RESULTS: Among the 266 patients, lung (48%), breast (17%), and melanoma (15%) were the most common primaries. At the time of SRS, 55 patients (21%) were undergoing ACT and 42 patients (16%) were on APT. ITH was identified pre-SRS in 67% of patients, increasing to 78% on post-SRS imaging sequences for the entire cohort. However, there was no significant correlation between ITH and ACT (p = 0.88) or APT (p = 0.85) vs no blood thinning therapy post SRS. Multivariate analysis revealed melanoma histology, thrombocytopenia, lower marginal doses, and larger lesion size predicted ITH (p = 0.001, 0.02, 0.02, and 0.001 respectively). CONCLUSIONS: Using microhemorrhage-sensitive MRI sequences, our data demonstrated a higher incidence of intratumoral hemorrhage in BM both at baseline and post SRS relative to demonstrated using only T1-non contrast sequences However, despite using this ultrasensitive imaging modality, no correlation was observed between APT or ACT and increased ITH risk. Our data suggests that specifically stopping ACT or APT in anticipation of SRS is likely not indicated however larger prospective randomized studies are warranted.