[Early results of irradiation of intracranial meningiomas using CyberKnife].

Meningiomas are frequently diagnosed intracranial lesions which cannot be resected radically in the majority of cases. Traditional radiotherapeutical techniques allow control of tumor growth in such situations. CyberKnife system may be used for radiosurgery and in sight hypofractionation. During 27 months 231 patient with intracranial meningiomas of different localization was treated in department for radiation therapy of Burdenko Neurosurgical Institute using CyberKnife system (Accuray Inc., USA). Mean age was 53 years. 55% of patients underwent previous surgical treatment, and diagnosis of meningioma was histologically verified. In 231 patient 374 targets were irradiated. Mean volume of irradiation reached 15.8 cm3 (range - 0.73-108.5 cm3). In 89% of cases hypofractionated therapy was used, in 10.1% we performed radiosurgery. Catamnestic data were available in 80 patients. Mean follow-up period was 11.6 months (6-27 months). Control of tumor growth was established in 100% of cases with WHO grade I tumors, in 66.7% of WHO grade II tumors and 60% in WHO grade III tumors. Deterioration after radiation treatment was observed in 16% of cases of 75 with control of tumor growth. In 8 cases worsening was due to radiation-induced reactions verified by MRI studies. Radiosurgical and hypofractionated treatment of meningiomas using CyberKnife is actual and highly-effective technique. Further investigations are needed to determine optimal standards of hypofractionated radiotherapy of meningiomas.