(CNN)On the morning of May 10, 2017, Howard Stern abruptly canceled his show.
Long-time fans who knew the radio host's reputation for never missing a day of work were alarmed. But the man who built his career on his willingness to bring up any topic, no matter how taboo, never talked about what actually happened that morning.
That's because he was being wheeled into surgery, to excise a growth on his kidney that doctors told him had a 90% chance of being cancerous, according to a story Wednesday in The Hollywood Reporter.
Up to that point, Stern had led a healthy life, virtually devoid of medical issues.
"And now all I'm thinking is, 'I'm going to die,'" he told THR. "And I'm scared sh*tless."
After the operation, Stern learned the growth was just a benign cyst. But the brush with death made Stern reflect on the life he'd been living.
Stern's new book is out next week
The revelations come as the radio host is about to release a new book, titled "Howard Stern Comes Again," on Tuesday. The 560-page tome is Stern's first book in more than two decades. It collects edited transcripts from interviews over the years, ranging from Lady Gaga to Jerry Seinfeld.
In between, Stern weighs in with autobiographical essays, including in the book's introduction, where he writes, "The interviews collected here represent my best work and show my personal evolution. But they don't just show my evolution. Gathered together like this, they show the evolution of popular culture over the past quarter century."
The self-described "King of All Media" expresses many regrets, including a narcissism that led him to be an absent father to his three daughters.
"I didn't know what was up and what was down, and there was no room for anybody else on the planet," he told The Hollywood Reporter.
Stern went to therapy as many as four days a week, but he's now down to two weekly sessions, according to THR.
On his website, Stern said that his all-time favorite interview was his 2015 conversation with Conan O'Brien. "I never stop hearing about that interview," Stern said.
He interviewed Trump dozens of times, but didn't vote for him
Stern was an ardent Hillary Clinton supporter in both 2008 and 2016. He never succeeded in landing her as a guest, but he had more than 40 interviews with Donald Trump. He sprinkles excerpts from those interviews throughout the book as well, The Hollywood Reporter says.
In 2016, CNN's K-File published audio clips of Trump's appearances on Stern's show over the course of 17 years. Trump made for a shocking radio guest, and joked with Stern about running for president, but Stern never supported him politically.
"A more self-serving person would have gone all in on Donald," Stern told THR. "I'd probably be the FCC commissioner or a Supreme Court justice by now."