Radiosurgery for malignant meningioma: results in 22 patients

Object. The initial treatment of malignant meningiomas in the past has incl uded surgical removal followed by fractionated external-beam radiotherapy. Radiosurgery has been added to the options for treatment of primary or recu rrent tumors over the last 10 years. The authors report their results of us ing gamma knife radiosurgery (GKS) to treat 22 patients over an 8-year peri od. Methods. Twenty-two patients who underwent GKS for malignant meningioma bet ween December 1991 and May 1999 were evaluated. Three patients were treated with GKS as a boost to radiotherapy and 19 for recurrence following radiot herapy. Outcome factors including patient survival, freedom from progressio n, and complications were analyzed. In addition, in the recurrent group, va riables such as patient age, sex, tumor location, target volume, margin dos e, and maximum dose were also analyzed. Univariate and multivariate analyse s were performed. Overall 5-year survival and progression-free survival estimates were 40% an d 26%, respectively. Age (p less than or equal to 0.003) and tumor volume ( p I 0.05) were significant predictors of time to progression and survival i n both univariate and multivariate analyses. Five patients (23%) developed radiation necrosis. Significant relationships between complications and tre atment variables or patient characteristics could not be established. Conclusions. Tumor control following GKS is greater in patients with smalle r-sized tumors (< 8 cm(3)) and in younger patients. Gamma knife radiosurger y can be performed to treat malignant meningioma with acceptable toxicity. The efficacy of GKS relative to other therapies for recurrent malignant men ingioma as well as the value of GKS as a boost to radiotherapy will require further evaluation.