Stereotactic Radiosurgery in the Multimodality Management of Residual or Recurrent Glioblastoma Multiforme.

Management options for residual or recurrent glioblastoma multiforme (GBM) are limited despite advances in surgical, chemotherapeutic, and radiotherapeutic techniques. Stereotactic radiosurgery (SRS) is often beneficial in such cases providing improved survival of patients, but still remains underutilized as part of the multimodality management of malignant gliomas. During the last 20 years, 297 patients with histologically proven residual or recurrent GBM underwent Gamma Knife surgery in the University of Pittsburgh. Retrospective analysis of outcomes revealed median survival after initial diagnosis of 18 months, and 1- and 2-year survival rates of 72.5 and 29.5%, respectively. Median survival from the time of SRS was 9 months. The use of modified RPA (recursive partitioning analysis) classification demonstrated superior survival in our series in comparison with historical data. Important prognostic variables include tumor volume <14 cm3, marginal radiation dose of ≥15 Gy, and younger age of the patients (<60 years). Adverse radiation effects (ARE) were noted in 23% of cases and were mainly controlled with corticosteroids. Combining SRS with bevacizumab resulted in further improvement of the overall and progression-free survival and decreased incidence of ARE. Nevertheless, for future application of SRS in patients with GBM, evaluation of its efficacy in a well-designed prospective controlled clinical trials seems mandatory.