SURG-52. LEPTOMENINGEAL DISSEMINATION AFTER GAMMATILE AND LITT IN HIGH GRADE ASTROCYTOMA PATIENTS

Abstract PURPOSE To present a case series of leptomeningeal dissemination after localized treatment with GammaTile or laser interstitial thermal therapy (LITT) in patients with high grade astrocytoma. BACKGROUND Leptomeningeal dissemination occurs primarily in glioblastoma patients with prolonged survival and those who undergo aggressive treatment courses. Targeted therapies such as GammaTile (which contains cesium-131 radiation-emitting seeds) or LITT may provide localized disease control following recurrence and serve as an immediate treatment modality for patients with recurrent disease in the weeks leading up to radiotherapy or systemic treatment. METHODS We retrospectively reviewed all consecutive patients with high grade astrocytoma treated with GammaTile or LITT who were found to have leptomeningeal dissemination of disease. Histological diagnosis, NGS and immunohistochemistry of tumor tissue were performed at both original diagnosis and at time of GammaTile placement or LITT procedure. Leptomeningeal dissemination was diagnosed through MRI findings on brain and spine. Cases were analyzed for time to development of leptomeningeal dissemination, median overall survival, survival from time of leptomeningeal dissemination diagnosis, time of dissemination to second radiation therapy. Tumor location, MGMT status and other molecular markers were also reviewed. RESULTS Out of 90 high grade astrocytoma patients treated with gamma tile radiation, 4 progressed to exhibit disseminated disease. There were 2 female patients, mean age was 50 years. Location of tumor was in the left temporal lobe in 3 patients and right temporal in 1. They were all IDH wild type. Two were MGMT methylated, two were non methylated. The median time from initial glioma diagnosis to LMD was 221 months (range 11-152) and overall survival after disseminated disease diagnosis was 7.5 weeks (range 3–13). CONCLUSION Leptomeningeal dissemination is a devastating complication of aggressive gliomas. Currently, there is no standard treatment for disseminated disease in high grade astrocytoma patients. Systemic therapy is needed following localized therapies to control disease. Further research into new therapies is needed to allow for better outcomes.