Howard Stern will talk about pretty much anything on his radio show, but a private health matter was off-limits.

In his new book, Howard Stern Comes Again — a collection of his interviews as well as self-reflection — and a sit-down with The Hollywood Reporter to promote it, Stern comes clean about a cancer scare that rocked him in 2017.

The Howard Stern Show host, 65, revealed how on May 10, 2017, he canceled his SiriusXM show, prompting speculation and theories from his devoted fans. While he returned to the air just days later, he lied to the audience about his absence, saying he had the flu. "Why is it such a big deal that I took a f***ing day off?" he asked on air.

Howard Stern reveals a cancer scare that he underwent surgery for in 2017. (Photo: Jeff Kravitz/FilmMagic) More

Stern now explained that the day in question he was actually in surgery. For the entire year prior, he had visited countless doctors to monitor a low white blood cell count discovered during a routine checkup — as well as a growth on his kidney, which he was told had a 90 percent chance of being cancerous.

"All I'm thinking is, 'I'm going to die,'" Stern recalled in the interview, his first time discussing the health issue publicly. "And I'm scared s***less."

However, after several hours in surgery, he learned that it had just been a scare and the growth turned out to be a tiny, harmless cyst.

The shock jock revealed that he kept the whole ordeal quiet, only telling his inner circle, including family (wife Beth Stern and three daughters), his Howard Stern Show sidekick Robin Quivers, a cancer survivor and, of course, his therapist.

Stern said going through that has made him face his mortality — and question if it’s time to turn off his microphone, travel with Beth and spend more time with his grown daughters. His contract with SiriusXM, which reportedly pays him $90 million a year, expires at the end of 2020.

"I'm at a place now where I am trying to figure out how to spend the rest of my life, however long that might be," he told THR. Though, he admitted, "It seems weird to me not to have this [show].”

In addition to discussing the cancer scare with THR, Stern also talked about his relationship with Donald Trump, who for years called into his show or dropped by. Stern said that while he was in contact with the president during the election — and Stern admitted, despite being a Hillary Clinton supporter, he thought she would have a hard time beating Trump — he really hasn’t spoken to him since a congratulatory exchange when Trump won in 2016.

"It was a difficult thing because there's a part of me that really likes Donald, but I just don't agree politically," Stern said. Though, he quipped, "A more self-serving person would have gone all in on Donald because I'd probably be the FCC commissioner or a Supreme Court justice by now."

Howard Stern Comes Again comes out on May 14. Order it on Amazon.

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