John McCain Just Finished His First Round Of Chemo And Radiation Treatment

John McCainis one tough cookie.

The Arizona senator marked a major milestone Friday, with the completion of his first round of chemotherapy and radiation treatments. Both the Republican senator and his daughter, Meghan McCain, celebrated the news with posts to social media.

“My father completed first round radiation/chemo,” Meghan McCain tweeted Friday. “His resilience & strength is incredible. Fight goes on, here’s to small wins.#fuckcancer.”

Doctors diagnosed McCainwith glioblastoma, a malignant brain tumor, in July while he was undergoing surgery for a blood clot.

Only days after his diagnosis, McCain returned to the Senate to participate in the debate about repealing theAffordable Care Act. The Arizona senator was one of three Republicans who voted against the repeal bill, which would have stripped millions of Americans of their health insurance.

Politicians from both parties overwhelmingly gave their support for McCain, including former President Barack Obama, who was his presidential campaign opponent in 2008.

“John McCain is an American hero & one of the bravest fighters I’ve ever known,” Obama wrote on Twitter. “Cancer doesn’t know what it’s up against. Give it hell, John.”

The 80-year-old senator began hisinitial treatment on July 31at the Mayo Clinic Hospital in Arizona and plans to return to work after the August recess.

His office did not immediately respond to a request for comment, but McCain posted his gratitude to medical staff on Instagram Friday:

McCain is already up and about. He posted a sunny photo to this Twitter account with his “amigos”Sen. Lindsey Graham (R-S.C.) and formerSen. Joe Lieberman (D-Conn.) Saturday.

You can’t keep a good man down.

This article originally appeared on HuffPost.