Life expectancy statistics for glioblastoma depend on the age of the patient, the type of treatment and the aggressiveness of the cancer, explains the American Brain Tumor Association. Generally, less than 10 percent of adults with glioblastoma survive more than five years after the original diagnosis.
Doctors grade brain tumors on a scale from I to IV. Grade-IV tumors are the most aggressive and fast-growing. Adults with grade-IV glioblastomas have a typical survival rate of one year, notes WebMD. Adults with grade-III glioblastomsas, also known as anaplastic astrocytomas, have a 50 percent chance of surviving two to three years, notes the American Brain Tumor Association. In contrast approximately 25 percent of children with grade-III or grade-IV glioblastomas survive five years after diagnosis.