Management of atypical and malignant meningiomas: role of high-dose, 3D-conformal radiation therapy

Objective Atypical and malignant meningiomas are at high risk for local fai lure. The role of radiation therapy (RT) and dose levels required to improv e tumor control are poorly defined. This study reviews our experience with RT. Material and methods Thirty-one patients underwent fractionated RT for atyp ical (AM, 15 patients) or malignant meningioma (MM, 16 patients) of the cra nium. Sixteen patients presented with primary and 15 with recurrent disease . Eight patients received RT following total resection, 21 patients after s ubtotal resection and 2 patient following biopsy only. RT was given using m egavoltage photons in 15 patients and combined photons and 160 MeV protons in 16 patients. Total target doses ranged from 50 to 68 (AM, mean 62) and f rom 40 to 72 (MM, mean 58) Gy or CGE (= cobalt-gray-equivalent). Results With mean observation time of 59 months (range: 7-155 months) actua rial local control rates at 5- and 8-years were similar for both histologie s (38% and 19% for AM and 52 and 17% for MM). However, significantly improv ed local control was observed for proton versus photon RT (80% versus 17% a t 5 years, p = 0.003) and target doses greater than or equal to 60 Gy for b oth, atypical (p = 0.025) and malignant meningioma (p = 0.0006). At time of analysis, 14/15 patients (93%) with AM and 6/16 (38%) with MM we re alive. Three patients (19%) with MM developed distant metastasis. Actuar ial 5- and 8-year survival rates for MM were significantly improved by use of proton over photon RT and radiation doses greater than or equal to 60 CG E. Three patients developed symptomatic radiation damage after 59.3, 68.4 a nd 72 Gy/CGE. Conclusion Conformal, high dose RT resulted in significant improvement of l ocal control for atypical and malignant meningiomas. Increased local contro l resulted also in improved rates of survival for patients with malignant m eningioma.