gms | German Medical Science

Objective: Meningioma is the most frequent benign tumour treated with Gamma Knife Surgery (GKS); however the assessment of its efficacy and safety in slowly growing tumours is an ongoing process, requiring analysis of long-term results. This multicenter study, still in progress, involves the experience of several European Gamma Knife Centres. We report on the efficacy of GKS for the treatment of meningiomas, clinical and radiological control, side effects and failures.

Methods: The data reported so far refer to the population retrieved between May 2007 and April 2008. The minimum follow-up period for inclusion was 60 months. All treatment protocols and follow-up data have been collected and verified retrospectively by one single person (AS). A preliminary descriptive analysis is presented.

Results: 4297 patients harbouring 4928 meningiomas treated between 1987 and May 2003 in twelve of the fifteen institutions involved in the study were evaluated. The median age was 57.5 years (range 7–92 years). The median tumour volume was 5.00cm³ (range 0.1–89.9cm³). The median tumour margin dose was 14.0Gy (range 6–40Gy) to a median 50% isodose line (range 20–97%). The median radiological follow-up was 54 months (median clinical follow-up 54.7 months). 161 patients of this population died in the observation interval. The volume of treated tumours decreased in 2,513 lesions (60%), did not change in 1,397 lesions (34%), and increased in 255 lesions (6%). The temporary morbidity rate after GKS was 6.6% and the permanent morbidity rate was 2.5%. The actuarial control rate was 93.8% at 5 years post GKS.

Conclusions: According to these provisional results GKS is a safe and non-invasive method of treatment of meningiomas, and the large number analysed confirms the conclusions already reported by previous studies, with a high tumour control and low morbidity rate even after a long-term follow-up period.