Patterns of recurrence after stereotactic radiosurgery for treatment of meningiomas

The purpose of this study was to evaluate patterns of failure after stereotactic radiosurgery (SRS) for meningiomas and factors that may influence these outcomes.

Based on a retrospective chart review, 279 patients were treated with SRS for meningiomas between January 1999 and March 2011 at Wake Forest Baptist Health. Disease progression was determined using serial imaging, with a minimum follow-up of 6 months (median 34.2 months).

The median margin dose was 12.0 Gy (range 8.8-20 Gy). Local control rates for WHO Grade I tumors were 96.6%, 84.4%, and 75.7% at 1, 3, and 5 years, respectively. WHO Grade II and III tumors had local control rates of 72.3%, 57.7%, and 52.9% at 1, 3, and 5 years, respectively. Tumors without pathological grading had local control rates of 98.7%, 97.6%, and 94.2% at 1, 3, and 5 years, respectively. Of the local recurrences, 63.1% were classified as marginal (within 2 cm of treatment field). The 1-, 3-, and 5-year rates of distant failure were 6.5%, 10.3%, and 16.6%, respectively, for Grade I tumors and 11.4%, 17.2%, and 22.4%, respectively, for Grade II/III tumors. Tumors without pathological grading had distant failure rates of 0.7%, 3.2%, and 6.5% at 1, 3, and 5 years, respectively. Wilcoxon analysis revealed that multifocal disease (p < 0.001) and high-grade histology (WHO Grade II or III; p < 0.001) were significant predictors of local recurrence. Additionally, male sex was a significant predictor of distant recurrence (p = 0.04). Multivariate analysis also showed that doses greater than or equal to 12 Gy were associated with improved local control (p = 0.015).

In this patient series, 12 Gy was the minimum sufficient margin dose for the treatment of meningiomas. Male sex is a risk factor for distant failure, whereas high-grade histology and multifocal disease are risk factors for local failure.