Role of gamma knife radiosurgery for recurrent or residual World Health Organization grade II and III intracranial meningiomas.

To analysis the role of gamma knife radiosurgery (GKRS) in treatment of the recurrent or residual World Health Organization (WHO) grade II and III meningiomas. Between 1995 and 2015, a total of 1163 meningioma patients were treated with GKRS at our single institute; 26 atypical and 6 anaplastic meningiomas were enrolled. The group consisted of 16 men and 16 women with a median age of 59.5 years (range 30-78 years). The median follow-up was 106.5 months (range 40-216 months). All were cases of tumour recurrence except 7 cases of residual lesions. Six patients were given fractionated radiotherapy before the initial course of GKRS (median dose, 56 Gy). The median tumour volume was 3035 mm (range 247-11400 mm). The median prescribed dose to high grade meningioma margin was 14 Gy (range 12-20 Gy,). The median prescribed dose to WHO II and III meningioma were 14 Gy (range 12-18 Gy) and 15 Gy (range 14-20 Gy), respectively. After radiosurgery, local tumour control rate was 50%. Tumour progression was observed in 28 patients; 16 recurrences were local (12 atypical and 4 anaplastic), 8 were marginal (7 atypical and 1 anaplastic), and 4 were distal (3 atypical and 1 anaplastic). Seven patients (21.88%) developed adverse radiation effects after GKRS. WHO grade was strongly associated with survival, with grade II showing a much longer survival ( = 0.01), and a prior history of radiation was associated with decreased survival ( = 0.003). Multivariate analysis showed that WHO grade (hazard ratio, HR: 5.051,  = 0.01) and prior radiation (HR: 5.763,  = 0.004) were independently associated with survival. WHO grade and a prior history of radiation therapy are reliable long-term predictors of overall outcome when treated with GKRS.