Chris Evans, 48, dropped the bombshell while he was speaking on his Friday morning breakfast show.
"It's a fine line between life and death, happiness and tragedy"
Speaking candidly, he said: "Thank you once again to Kenney Jones, of The Who, who was diagnosed with prostate cancer a couple of years ago and since recovery has been a fundraiser and supporter of Prostate Cancer UK.
"Prostate cancer, and colon cancer of course, are one of the most survivable forms of cancer there is, if caught early enough.
"It's a fine line between life and death, happiness and tragedy."
The dad-of-three continued: "And I've got to say I'm in the middle of a prostate issue right now! I couldn't stop. I have not been able to stop since Christmas - peeing - or wanting to go. So I've gone to the doctor.
"I've done all the internet stuff that you shouldn't do, I've gone on the internet, scared myself half to death, then gone to see the doctor.
"And we really should do it the other way round. However I'm in the middle of the tests."
Traffic presenter Lynn Bowles replied: "You seem ok about that?"
Chris replied: "Well, you've got to be. I've completely changed my tune on this over the last couple of years. So there you go.
"If you are worried about anything just go and sort yourself out - if not for you, for your family."
Chris is married to golfer Natasha Shishmanian, with whom he has two young sons, Noah, five, and Eli, 18 months.