When 90 percent of the tumor is removed successfully, the average life expectancy following a diagnosis of glioblastoma is 14 to 15 months, according to Everyday Health. The overall survival rate for glioblastoma is less than 5 percent at the 5-year mark.
Glioblastoma is a grade IV astrocytoma that is characterized by aggressive growth, notes Everyday Health. Although it can afflict anyone, those age 50 and older are most often affected. Men are more likely than women to develop this form of brain cancer. Children can develop glioblastoma, although it is not as common. Glioblastoma usually develops in the cerebrum, which is the area of the brain responsible for thinking. In children, it is typically found in the cerebellum, cerebrum or brainstem.