The American Brain Tumor Association indicates that the average life expectancy for adults who receive standard treatment for giloblastoma is between two and three years. For adults diagnosed with more aggressive giloblastoma that requires treatment with temozolamide and radiation therapy, the average life expectancy is 14.6 months. The rate of adults who survive at least two years is 30 percent, and almost 10 percent survive longer than five years.
The Brain Tumor Association defines its median survival time as the time during which an equal number of patients do better and an equal number of patients do worse. According to this scale, children with high grade tumors of at least grade III or grade IV perform better than adults, with an average of 25 percent surviving for five years or longer. Also, patients who undergo methylation, which is the process of medically shutting off the MGMT gene, benefit with prolonged survival rates. However, the Brain Tumor Association states that not all giloblastomas have the same biological abnormalities. This is thought to be the reason why different patients respond in different ways while undergoing the same treatment and also why patients with the same tumor see different outcomes. Researchers continue to study what long-term survivors have in common to develop more personalized plans to give patients the best treatment possible.