Glioblastoma is the most common and aggressive primary malignant brain tumor in adults. The American Cancer Society (ACS) estimated approximately 22,070 new cases of malignant tumors of the brain or spinal cord in the United States in 2009 and approximately 12,920 deaths. Most brain tumors start in astrocytes, which are a type of nonneuronal, or glial, brain cell; these tumors are called astrocytomas. According to the ACS, approximately 30% of brain tumors are astrocytomas. Glioblastoma is the highest-grade astrocytoma and has the fastest growth rate. Approximately 65% to 70% of astrocytomas are glioblastomas. Despite therapeutic advances, most patients with glioblastoma have a poor prognosis; the median survival is 12 to 15 months. Standard treatment for newly diagnosed glioblastoma is surgical resection followed by radiotherapy and temozolomide. Few treatment options are available for recurrent glioblastoma.