John McCain
John McCainReuters

Senator John McCain, who ran for president in 2008 on the Republican ticket, has been diagnosed with brain cancer, the senator’s office reported Wednesday night.

The 80-year old senator has been diagnosed with primary glioblastoma, one of the most aggressive forms of brain cancer.

The tumor was discovered during a routine physical the senator underwent last week. After complaining of fatigue and double vision, McCain was given a CT scan, which revealed a clot just below his left eyebrow.

Doctors removed the clot in a four-hour operation, and said the senator was recovering well. According to McCain’s office, the senator has returned home to recuperate and has yet to decide when he will return to the Senate.

Despite the operation, however, experts warn that additional tumors are likely to reappear, given the aggressive nature of primary glioblastoma.

“It’s a very aggressive tumor,” Dr. Sanjay Gupta, who evaluated McCain’s medical records ahead of his 2008 presidential bid, told CNN. Dr. Gupta said the average life-expectancy once primary glioblastoma has been discovered is about 14 months. The chair of Montefiore Hospital’s neurosurgery department, Dr. Eugene Flamm, told The New York Times the median life-span is 16 months.

But as University Hospitals Case Western Reserve neurosurgeon Dr. Andrew Sloan told Fox News, with experimental treatments now available, some patients are able to live as long 10 years with the cancer.

“Despite the grim prognosis, we do have 2, 5, and occasionally, 10 year survivors.”

The senator will be unable to begin any additional treatments to combat the cancer, including radiation treatment, for at least three to four weeks as he recovers from the surgery.

McCain has been treated in the past for cancer, with Stage 0 melanoma skin cancer tumors removed in 1993, 2000, and again in 2002.

McCain, who has served in public office since 1983, has represented Arizona in the US Senate since 1987. After serving two terms in the US House of Representatives, McCain won six consecutive elections to the Senate, most recently defeating Ann Kirkpatrick in 2016 by 13 points.

As a naval aviator in the Vietnam war, McCain was shot down while piloting an A-4E Skyhawk over North Vietnam in 1967. After being taken prisoner, McCain was bayoneted, severely beaten, and denied medical treatment for weeks. McCain suffered torture and beatings at the hand of North Vietnamese officials before being released in 1973, following the Paris Peace Accords which ended American combat in the war.