AARP Eye Center
After being operated on to remove a blood clot above his left eye, Sen. John McCain, 80 (R-Ariz.), has been diagnosed with primary glioblastoma, an especially aggressive type of brain tumor. The tumor forms in the tissue of the brain and spinal cord, according to the American Brain Tumor Association (ABTA).
Glioblastoma represents 14.9 percent of all primary brain tumors and 55.4 percent of all gliomas, a general category of brain tumor. It also has the highest number of cases of all malignant tumors, with an estimated 12,390 new cases predicted in 2017. Peak incidences occur from ages 55 to 85 and are rare in people under 40, ABTA Chief Science Officer Nicole Willmarth tells AARP. They also tend to affect more men than women.
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According to ABTA, the tumors arise from astrocytes, or the star-shaped cells that make up the supportive tissue of the brain. They reproduce quickly and are supported by a large network of blood vessels, making them highly cancerous.
Symptoms to watch
Because glioblastomas can grow rapidly, the most common symptoms are usually caused by increased pressure in the brain. They can include headache, nausea, vomiting and drowsiness. Depending on the tumor's location, patients may develop a variety of other symptoms, such as weakness on one side of the body, memory and/or speech difficulties, and visual changes.