High efficacy of fractionated stereotactic radiotherapy of large base-of-skull meningiomas: Long-term results

Purpose: Large skull-base meningiomas are difficult to treat due to their p roximity or adherence to critical structures. We analyzed the long-term res ults of patients with skull-base meningiomas treated by a new approach with high-precision fractionated stereotactic radiotherapy. Patients and Methods: One hundred eighty-nine patients with benign meningio mas were treated with conformal fractionated stereotactic radiotherapy betw een 1985 and 1998. Patients were undergoing a course of radiotherapy either as primary treatment, following subtotal resection, or for recurrent disea se. The median target volume was 52.5 mL (range, 5.2 to 370 ml.). The mean radiation dose was 56.8 Gy (+/- 4.4 Gy). Follow-up examinations, including magnetic resonance imaging, were performed at 6-month intervals thereafter. Results: The median follow-up period was 35 months (range, 3 months to 12 y ears). Overall actuarial survival for patients with World Health Organizati on (WHO) grade I meningiomas was 97% after 5 years and 96% after 10 years. Local tumor failure was observed in three of 180 patients with WHO grade I tumors and was significantly higher in two of nine patients with WHO grade II tumors. A volume reduction of more than 50% was observed in 26 patients (14%). Preexisting cranial nerve symptoms resolved completely in 28% of the patients. Clinically significant treatment-induced toxicity was seen in 1. 6% of the patients. No treatment-related deaths occurred. Conclusion: The results of this study demonstrate that fractionated stereot actic radiotherapy is safe and effective in the therapy of subtotally resec ted or unresectable meningiomas. The overall morbidity and incidence subacu te and late side effects of this conformal radiotherapy approach were low.