RONC-10. OUTCOMES OF STEREOTACTIC RADIOSURGERY FOR PILOCYTIC ASTROCYTOMA: AN INTERNATIONAL MULTICENTER STUDY

Abstract BACKGROUND The utility of radiosurgery is not well documented for pilocytic astrocytoma. We analyzed the efficacy and prognostic factors associated with Gamma Knife radiosurgery (GKRS) for pilocytic astrocytoma in an international multicenter trial. METHODS Nine medical centers from the International Gamma Knife Research Foundation provided data. Patients treated with single session GKRS with histologic diagnosis of pilocytic astrocytoma were eligible. Patient, tumor, and treatment variables were analyzed. RESULTS 141 patients with a median age 13.9 years (range: 2-84) were included. Median follow up was 67.3 months. Twenty-one (15%) had radiotherapy (RT) and 11 (8%) had chemotherapy prior to GKRS. Median margin dose: 14 Gy (range: 4-22.5). Median tumor volume:3.45cc (range: 0.17-33.7). Overall survival at 3, 5 and 10 years from GKRS was 96.8%, 95.7% and 92.5%, respectively. Thirty-four patients progressed resulting in progression-free survival (PFS) at 3, 5, and 10 years of 80.8%, 74.0%, and 69.7%, respectively. For patients