Fox News' Sean Hannity reacted Monday to talk radio pioneer Rush Limbaugh's announcement that he has been diagnosed with advanced-stage lung cancer.

"It just hit me like a dime, like a ton of bricks, like a Mack truck -- whatever cliche you want to use, that's it," he said.

RUSH LIMBAUGH ANNOUNCES CANCER DIAGNOSIS

Hannity, whose syndicated radio show follows Limbaugh's over many stations, told his listeners he had an entirely different rundown planned until he heard the 69-year-old broadcaster's announcement on his eponymous radio program moments earlier. Hannity said he has known Limbaugh and his family for decades and that they are all "incredibly brave" people.

"[Rush was] so incredibly stoic and courageous [in his announcement], because like everything else he's ever done in his career, he's inspiring," he added.

Limbaugh began the final segment of Monday's program by telling listeners that he had news he had to share with them, though that he struggled with whether to announce it publicly.

"It’s a struggle for me because I had to inform my staff earlier today,” he said. “I can’t help but feel that I’m letting everybody down. The upshot is that I have been diagnosed with advanced lung cancer."

“I told the staff today that I have a deeply personal relationship with God that I do not proselytize about, but I do, and I have been working that relationship tremendously,” the Missouri native continued. "I am, at the moment, experiencing zero symptoms."

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On his own radio show, Hannity credited Limbaugh with paving the way for him to have his own career in talk radio, which began in the early 1990s before the inception of Fox News Channel.

He said that one of his biggest breaks came when Limbaugh asked him to substitute host the "Rush Limbaugh Show" and remarked that the host took it well when Hannity dropped the famous Golden EIB Microphone.

"We are praying for a speedy recovery -- and for years more of Excellence in Broadcasting," he said -- referencing Limbaugh's "EIB Network" tag. "It's deeply personal."

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He added that their mutual friend and fellow radio host Mark Levin has also credited Limbaugh with pioneering the conservative talk radio field.

"Everybody that knows what you've done -- how you've taken a lot of hits over the years, standing up for this country, our Constitution, your belief in God [and] your belief in life, you fighting fights every single solitary day to make this a more perfect union, a better country ... we're all praying for you."

Fox News' Brian Flood contributed to this report.