Inside John McCain's brain cancer fight

U.S. Senator John McCain, 80, rocked the political and medical world last week when his office announced he had been diagnosed with an extremely aggressive brain tumor called Glioblastoma multiforme, discovered after having surgery to remove a blood clot above his left eye.

Dr. Nina Paleologos, a neuro oncologist at Advocate Good Samaritan Hospital in Downers Grove, Ill. and Advocate Lutheran General Hospital in Park Ridge, Ill., one of only a handful of doctors in the country who specializes in treating the tumor, says it was among the hardest of brain cancers to treat because of how aggressive it is and that it tends to recur even after treatment.

"One of the most difficult things about it is that it is not encapsulated in any way - it's got roots or tendrils of cells that infiltrate far away into the brain from the main mass and you can't see them because they're microscopic," she says. "There's always disease left behind, which by its nature is constantly trying to keep growing."

Glioblastoma tumors form in the supportive tissue of the brain and are highly malignant because the cells reproduce quickly and are supported by a large blood vessel network, according to the American Brain Tumor Association.

These tumors may cause symptoms related to where they are in the brain, such as weakness on one side of the body, language difficulties or they may present with symptoms of increased pressure in the brain. Because they contain abnormal blood vessels, they may also present with a blood clot as in Sen. McCain's case, says Dr. Paleologos.

More than 20,000 patients are diagnosed with the tumor each year - a percentage of which Dr. Paleologos treats daily.

The neuro oncologist says Sen. McCain has already undertaken the best initial approach to treatment by having as much of the tumor surgically removed from his brain as possible. From there, he will receive a combination of radiation and chemotherapy, with the possibility of additional clinical trials in conjunction to the more conventional treatments.

"We now know that not all Glioblastoma tumors are the same, and treatment is moving toward more specific targeted therapies depending on the molecular make up of a patient's tumor," says Dr. Paleologos.

Unfortunately, the median average survival time is approximately 14.5 to 15 months, she says. Around 25-35 percent of patients will live for two years past the diagnosis. Only 10 percent survive for more than five, and that percentage goes down the older the patient.

Dr. Paleologos says the long-term prognosis of those with the diagnosis has increased over the last several years, and that each patient is different and has their own fight ahead of them.