Ron Rivera of Washington Football Team cancer-free

Washington Football Team coach Ron Rivera was declared cancer-free after a checkup Thursday.

Rivera, who announced on Aug. 20 that he had squamous cell cancer, tweeted thanks Thursday for the support he received during his treatment and recovery.

"Thank you everyone for your prayers, letters, texts & notes of encouragement & support. It truly made a difference in my treatment & recovery!#RiveraStrong @WashingtonNFL," he wrote.

That social media post came after both his wife, Stephanie, and daughter, Courtney, took to social media earlier Thursday to announce that Rivera had defeated cancer.

"Prayers have been answered. Thx to all the Drs & nurses who 'Coached up' @RiverboatRonHC and me and gave us the winning game plan to defeat cancer. The PET scan said it all, cancer you lost this fight! #RiveraStrong," Stephanie Rivera tweeted.

Added Courtney, who works as a producer for Washington's social media: "Just gotten off the phone with mom and dad leaving the hospital @RiverboatRonHC is officially cancer free!!!"

Ron Rivera needed to undergo seven weeks of treatment for the cancer during the season, which included three rounds of chemotherapy and proton therapy five days a week.

He ended his treatment on Oct. 26. That day, a video captured the moment when he walked down the hallway of the Inova Schar Cancer Institute flanked by cheering medical personnel -- all wearing black "Rivera Strong" T-shirts -- culminating in his ringing a bell to signify the end.

Though his prognosis was good from the start, the treatments took a toll. He needed to use a golf cart during practice and his energy level decreased. But he missed only three practices and never missed a game, though he admitted that one week early in the season he was close to stopping. But he pushed through.

He did have to adjust his daily routine. He'd take naps throughout the day -- after videoconference sessions with reporters, for example. His wife or daughter would drive him home in the late afternoon or early evening as fatigue overwhelmed him.

"At times you get nauseous," he said in October. "At times your equilibrium is messed around with, almost a sense of vertigo. And then the nausea. It hits you at any time, anywhere. But the fatigue, going out to practice it limited me, and that bothers me because I can't coach the way I coach."

Rivera, 59, lost 36 pounds and weighed 232 at one point -- six pounds under his playing weight with the Chicago Bears in the 1980s.

"I was amazed. Usually our patients, halfway in, stop working," Dr. John Deeken, the oncologist and president of the Inova Schar Cancer Institute, told ESPN in November. "Most of our patients toward the end of their treatment are very close to needing to be hospitalized because there are so many complications."

Rivera and Washington were rewarded as it won the NFC East. Washington won five of its last seven games to finish 7-9 before losing to Tampa Bay in the wild-card round of the playoffs. Players said throughout the season that watching Rivera battle cancer helped inspire them. The coaches said it made a difference.

"This team, watching him, understood when he said we're going to have opportunities and we're going to win and we'll change the culture; they saw it firsthand because they saw what he'll go through," said assistant defensive backs coach Richard Rodgers in December. "He stayed consistent in what he wanted done."

Rivera has said he'd like to become an advocate for affordable health care. His brother Mickey died of pancreatic cancer in 2015.

"After going through it and seeing just how expensive it is ... you think, 'Gosh, how can people afford this that aren't in the situation or the position that I'm in?'" he said in November. "That's really helped to shape my views, just saying and thinking to myself, we need to have some sort of affordable care in the United States for everybody."