Arizona Sen. John McCain, whose absence from Washington forced Republicans to abruptly cancel a vote on healthcare legislation, announced Wednesday night that he had been diagnosed with brain cancer.

After a procedure Friday in Phoenix to remove a blood clot above his left eye, a pathology report “revealed that a primary brain tumor known as a glioblastoma was associated with the blood clot,” according to a statement issued by McCain’s Washington office. [restrict

“The senator and his family are reviewing further treatment options,” the statement added, saying McCain’s “underlying health is excellent.”

Though no two cases are the same, glioblastoma — an aggressive type of cancer — can be difficult to treat, according to the website of the Mayo Clinic, which is overseeing McCain’s treatment.

Surgeons can try to remove as much of a tumor as possible. But because glioblastoma grows into brain tissue, complete removal is impossible. Radiation and chemotherapy are common treatments.

Median survival is 15 months, according to the American Brain Tumor Assn., although a 2009 study found that 1 in 10 patients can survive five years or longer.

McCain, who turns 81 next month, is serving his sixth term in the Senate. His return to Washington is uncertain, pending further consultation with his doctors.

His absence, however long, will greatly complicate the task facing Senate Majority Leader Mitch McConnell, who was already struggling to push through an expansive agenda, including tax reform and the GOP’s embattled healthcare overhaul.

McCain’s current and former colleagues react to his diagnosis

Without Arizona’s senior senator on hand, there are just 51 Republicans in the Capitol — the slimmest of majorities.

In announcing the surgery to remove the blood clot last week, McCain’s office played down the procedure, describing it as a minimally invasive operation through an eyebrow incision. The clot was discovered, his office said, during an annual physical.

The two-time presidential hopeful, who has a history of skin cancer and a number of permanent injuries from his 5 1/2-year captivity as a prisoner of war in Vietnam, has nevertheless been among the most vigorous members of Congress; a favorite hobby for the Senate Armed Services Committee chairman is flying to war zones and other world hot spots whenever the Senate takes a break.

His absence derailed plans for a vote this week on Republican efforts to repeal and replace the Affordable Care Act, which has been the GOP’s top legislative and political priority for close to a decade. Without a unified GOP, McConnell was short of the 50 votes needed to bring the bill to the floor for debate, and last weekend announced an indefinite delay.

The legislative effort subsequently collapsed when several Republican senators announced their opposition to the plan, which would make deep cuts in Medicaid and result in tens of millions of Americans going without health insurance.

McCain was among those expressing concern about the draft legislation; Arizona has added hundreds of thousands to its insurance rolls as a result of Medicaid’s expanded coverage, and Republican Gov. Doug Ducey, among other critics, has stated his opposition to the GOP’s legislation.

In the statement from his office, McCain expressed gratitude for “the outpouring of support” since his initial diagnosis. “He is in good spirits as he continues to recover at home with his family,” the statement said. “He is confident that any future treatment will be effective.”

His daughter Meghan issued her own comments on behalf of the family, saying, “It won’t surprise you to learn that in all this the one of us who is most confident and calm is my father. He is the toughest person I know. The cruelest enemy could not break him.”

Warm wishes came from across the political spectrum, reflecting the bipartisan regard and respect that McCain has engendered.

President Trump said his family was praying for McCain and his family. “Get well soon,” the president said.

Former President Obama, who bested McCain to win the White House in 2008, said: “John McCain is an American hero & one of the bravest fighters I’ve ever known. Cancer doesn’t know what it’s up against. Give it hell, John.”

Former President Clinton wrote: “As he’s shown his entire life, don’t bet against John McCain. Best wishes to him for a swift recovery.”

His wife, Hillary Clinton — who forged an improbable friendship with McCain when she served as New York’s Democratic senator — added: “John McCain is as tough as they come. Thinking of John, Cindy, their wonderful children & their whole family tonight.”

Former Alaska Gov. Sarah Palin, McCain’s 2008 running mate, wrote: “John McCain is one tough fighter — we know he’ll face this diagnosis with courage and strength.”

His fellow Arizona senator, Republican Jeff Flake, said, “Tough diagnosis, but even tougher man.”

McCain’s diagnosis has an eerie parallel to 2009, when Democrats were battling to pass the Affordable Care Act, or Obamacare as it has come to be known.

In 2008, the bill’s foremost champion, Sen. Edward M. Kennedy, was diagnosed with the same type of brain tumor. He died 15 months later, in August 2009, denying Democrats a key vote needed for passage of the legislation.

Eventually, after Kennedy’s seat was filled by a Republican opponent of Obamacare, Democrats managed to pass the bill without a vote to spare. [/restrict]