Approximately 51 000 primary brain tumors are diagnosed in the United States each year, 36% of which are gliomas.1Of these, half are glioblastoma (GBM), or World Health Organization grade IV astrocytoma. Glioblastoma is the most aggressive form of glioma and, despite recent advances, continues to have a grim prognosis. The current standard of care for GBM begins with maximal safe surgical resection. After surgery, the combination of radiotherapy (RT) with temozolomide followed by adjuvant temozolomide therapy was shown to be significantly, although modestly, better than RT alone in a phase 3 clinical trial coordinated by the European Organization for Research and Treatment of Cancer and the National Cancer Institute of Canada.2Median overall survival in the chemoradiotherapy arm was 14.6 months compared with 12 months in the RT arm. Perhaps more importantly, however, the percentage of patients alive at 2 years increased from approximately 10% to approximately 26%.