What is glioblastoma? Glioblastoma is an aggressive cancer that is the most common of all malignant brain tumors. A glioblastoma is, defined as a grade IV astrocytoma, a type of tumor that grows from the star-shaped cells that make up the supportive tissue of the brain.Unlike most other cancers, brain tumors do not spread to other parts of the body. They kill by interfering with normal body function, depending on their location. What are some symptoms of a glioblastoma? Depending on the location of the tumor, a patient can have seizures, headaches, blurred vision and confusion. “If it affects the portion of the brain that controls your strength, and one half of the body will be weak, it could affect your speech, 2. Sometimes double vision, 3. The inability to understand or express yourself, 4. Even cognitive problems or understanding what you’re listening to, or the lack of insight,