As a young Navy flyer, McCain’s plane was shot down during a 1967 bombing mission over North Vietnam. He was captured and became a prisoner of war in the infamous “Hanoi Hilton” prison camp.
He entered politics in 1982 when he was elected to the House of Representatives. He became a senator in 1986 and became a stalwart of conservatism.
He was unsuccessful when he sought the Republican nomination for president in 2000. He got the nomination in 2008; however he lost to Barack Obama.
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Family, friends and politicians on both sides of the aisle shared their condolences.
In a statement former President George W. Bush called McCain “a man of deep conviction.”
“He was a public servant in the finest traditions of our country. And to me, he was a friend whom i'll deeply miss,” Bush’s statement read. "Laura I send our heartfelt sympathies to Cindy and the entire McCain family, and our thanks to God for the life of John McCain."
Tributes from world leaders also flowed from social media. Canada Prime Minister Justin Trudeau called McCain “an American hero and patriot.” Marise Payne, Australia’s new foreign minister, said democracy “has lost a giant.” British Prime Minister Theresa May said it was “an honor” to call McCain a friend of the United Kingdom.
Doctors discovered John McCain’s brain tumor after he underwent surgery in July 2017 to remove a blood clot from above his eye. He was previously diagnosed with melanoma in 1993, 2000 and 2002, and underwent treatment each time. Those cancers did not spread, according to John McCain’s doctors.
Glioblastoma is a particularly aggressive form of cancer and the prognosis is often poor, according to the American Brain Tumor Association. The average survival rate for patients with malignant glioblastoma is around 14 months if the person gets treatment. Around 10 percent of patients with the disease live for five years or longer.
The Associated Press contributed to this report.