BACKGROUND:

Gamma knife radiosurgery (GKRS) is recognized as an important treatment modality for meningioma.

OBJECTIVE:

To analyze the long-term outcomes in meningioma patients treated with GKRS to determine the risk factors related to treatment failure and peritumoral edema (PTE) development.

METHODS:

Between 1998 and 2010, 770 consecutive patients were treated with GKRS for intracranial meningioma. After the exclusion of patients with follow-up periods of less than 5 yr and those with neurofibromatosis, multiple meningiomas, nonbenign meningioma, or radiotherapy, a total of 424 patients were enrolled in this study. The median follow-up duration was 92 mo. The median tumor volume was 4.35 cm3, and the median marginal dose was 14 Gy.

RESULTS:

The overall local tumor control rate was 84%. The actuarial tumor control rates were 91.7% and 78.9% at 5 and 10 yr, respectively. The tumor control rate of a radiologically diagnosed tumor was higher than that of a grade I tumor (82% vs 70.1% at 10 yr, P = .001). In multivariate analysis, factors associated with tumor progression were female sex (hazard ratio: 0.5, P = .025) and a previous history of craniotomy (hazard ratio: 1.9, P = .009). Symptomatic PTE was identified in 36 (8.5%) patients, and the factor associated with poor PTE was the presence of PTE before GKRS (odds ratio: 4.6, P < .001). Permanent complication rate was 4%.

CONCLUSION:

GKRS appears to be an effective treatment modality for meningioma with long-term follow-up. However, the identification of delayed tumor progression in our study suggests that extended follow-up data should be collected after GKRS.