Stereotactic radiosurgery of World Health Organization grade II and III intracranial meningiomas: Treatment results on the basis of a 22-year experience

Background: A study was undertaken to define the variables associated with tumor control and survival after single-session stereotactic radiosurgery (SRS) for patients with atypical and malignant intracranial meningiomas. Methods: Fifty patients with World Health Organization (WHO) grade II (n = 37) or grade III (n = 13) meningiomas underwent SRS from 1990 to 2008. Most tumors were located in the falx/parasagittal region or cerebral convexities (n = 35, 70%). Twenty patients (40%) had progressing tumors despite prior external beam radiation therapy (EBRT) (median dose, 54.0 grays [Gy]). The median treatment volume was 14.6 cm ³; the median tumor margin dose was 15.0 Gy. Seven patients (14%) received concurrent EBRT (median dose, 50.4 Gy). Follow-up (median, 38 months) was censored at last evaluation (n = 28) or death (n = 22). Results: Tumor grade correlated with disease-specific survival (DSS) (hazard ratio [HR], 3.4; P =.008), local tumor control (HR, 2.4; P =.02), and progression-free survival (PFS) (HR, 2.6; P =.02) on univariate analysis, but not on multivariate analysis. Multivariate analysis showed that having failed EBRT and tumor volume >14.6 cm ³ were negative predictors of DSS and local control (HR, 3.0; P =.02 and HR, 4.4; P =.01; HR, 3.3; P =.001 and HR, 2.3; P =.02;, respectively). Having failed EBRT was a negative predictor of PFS (HR, 3.5; P =.002). Thirteen patients (26%) had radiation-related complications at a median of 6 months after radiosurgery. Conclusions: Tumor progression despite prior EBRT and larger tumor volume are negative predictors of tumor control and survival for patients having SRS for WHO grade II and III intracranial meningiomas.