Radiosurgical boost for primary high-grade gliomas

The purpose of this study was to retrospectively evaluate the survival of patients with high-grade gliomas treated with external beam radiotherapy with or without radiosurgical boost. From July 1993 to April 1998, 32 patients were selected, 15 of which received radiosurgery. Inclusion criteria were age > 18 years, histological confirmation of high-grade glioma, primary tumor treatment with curative intent, unifocal tumor and supratentorial location. All patients were found to be in classes III-VI, according to the recursive partitioning analysis proposed by the Radiation Therapy Oncology Group. The median interval between radiotherapy and radiosurgery was 5 weeks (range 1-13). Treatment volumes ranged from 2.9 to 70.3 cc (median 15.0 cc). Prescribed radiosurgery doses varied from 8.0 to 12.5 Gy (median 10.0 Gy). Radiosurgery and control groups were well balanced with respect to prognostic factor distributions. Median actuarial survival time in radiosurgery and control groups was 21.4 months and 11.6 months, respectively (p = 0.0254). Among patients with KPS > 80, median survival time was 11.0 months and 53.9 months in the control and radiosurgery groups, respectively (p = 0.0103). Radiosurgery was the single factor correlated with survival on Cox model analysis (p = 0.0362) and was associated with a 2.76 relative reduction in the risk of cancer death (95% confidence interval (CI) 1.07-7.13). Our results suggest that radiosurgery may confer a survival advantage for patients in RPA classes III-VI, especially for those with Karnofsky performance status >80. The definitive role of radiosurgical boost for patients with high-grade gliomas awaits the results of randomized trials.