NCOG-48. TRANSFORMATION FROM LOW GRADE MENINGIOMA AND PROGNOSTIC FACTORS FOR SHORTER TIME TO RECURRENCE OF WHO GRADE III MENINGIOMA DIAGNOSIS

Abstract

Abstract BACKGROUND WHO grade III meningiomas are rare, and clinical outcomes data are limited. To address this problem, we analyzed a single institution retrospective cohort of patients with WHO grade III meningiomas. METHODS Patients who underwent resection of WHO grade III meningiomas between 1983 and 2019 with available follow-up data were included. Treatment, local recurrence, and overall survival rates were obtained. Kaplan-Meier analysis, log rank tests, and Student’s t tests were used for statistical analyses. RESULTS Ninety consecutive patients met inclusion criteria. Median follow-up was 3.2 years (IQR: 1.2-7.9), median age was 58 years (IQR: 46-67). Twenty-three patients (26%) underwent resection alone, and 58 (64%) underwent resection with adjuvant radiotherapy. Fifty-one patients developed local recurrences, with median time to recurrence of 1.0 year (IQR: 0.6-2.9) and higher MIB-1 labeling index for tumors that recurred within 1 year (25% versus 17%, p=0.04). There was a median of 2 recurrences per patient (IQR: 1-3), with a median of 2 resections and 2 radiotherapy courses for initial and salvage treatments. Thirty-nine patients with recurrences died, with median overall survival of 3.7 years (IQR: 1.8-8.8). Thirty-seven patients (41%) had prior low grade meningioma diagnoses with subsequent transformation to grade III, including 6 (7%) with grade I, 16 (18%) with grade II, and 15 (17%) with unknown grade. There was a median of 1 low grade recurrence per patient (IQR: 0-3) before transformation to grade III, which occurred a median of 4.3 years (IQR: 2.4-9.9) after initial diagnosis. Prior low grade diagnosis was associated with shorter time to recurrence of WHO grade III meningioma (p=0.01), and worse overall survival (p=0.03). CONCLUSION Patients with WHO grade III meningioma have poor outcomes despite aggressive multimodal therapy, and there is an urgent, unmet need for new high grade meningioma treatments.