An estimated 43,800 new cases of primary CNS system tumors were diagnosed in the United States in 2005. Approximately 18,500 were malignant, representing 1.35% of all cancers diagnosed that year. Malignant CNS tumors caused approximately 13,000 deaths in 2005. On the basis of data provided by the Surveillance, Epidemiology, and End Results (SEER) Program, Deorah and colleagues found that the incidence of brain cancer increased until 1987, when the annual percentage of change reversed direction. The elderly experienced an increase in brain cancer until 1985, but their rates were stable thereafter. Overall, however, the incidence of glioblastoma has been increasing, with survival unchanged over the past 2 decades.