The Influence of Adjuvant Radiotherapy in Atypical and Anaplastic Meningiomas: A Series of 88 Patients in a Single Institution

OBJECTIVE: Atypical and anaplastic meningiomas (World Health Organization classification grade II and III) represent a small and heterogeneous subgroup of meningiomas that has a more aggressive biological nature and higher frequency of recurrence. The atypical form accounts for 4.7%-7.2%, whereas the anaplastic type accounts for 1%-2.8% of all meningiomas. The aim of this study is to evaluate the role of postoperative radiotherapy on overall survival and progression-free survival in patients operated for atypical and anaplastic meningiomas. METHODS: A retrospective analysis of the patients operated at the Clinic of Neurosurgery, Clinical Center of Serbia, Belgrade, between January 1, 1995 and December 31, 2006 was performed. In that period 88 lesions met the histologic criteria for atypical (75) and anaplastic (13) meningiomas. Postoperative radiotherapy was conducted in 63.6% of patients. RESULTS: At a median follow-up of 67.4 months the overall survival was 68 months and the 5-year survival was about 54.5%. The median survival was 76 months with surgery and adjuvant radiotherapy and 40 months with surgery alone (log rank = 7.4; P = 0.006). Recurrent disease occurred in 58 patients (65.9%). Median time between first surgery and tumor recurrence in patients undergoing radiotherapy was 51 months, whereas in the nonirradiated group it was 24 months (log rank = 17.7; P < 0.001). Multivariate analysis identified as recurrence-predicting factors anaplastic histotype (hazard ratio = 2.9; P = 0.003) and postoperative radiotherapy (hazard ratio = 4.5; P < 0.001). CONCLUSIONS: The addition of adjuvant radiotherapy to surgery for atypical and anaplastic meningiomas resulted in a clinically meaningful and statistically significant survival benefit.