"I had no idea," Stiller told Stern while on Sirius XM's The Howard Stern Show Tuesday. "At first, I didn't know what was gonna happen. I was scared. It just stopped everything in your life because you can't plan for a movie because you don't know what's gonna happen."
Stiller, 50, credits early detection with the prostate-specific antigen test, or PSA, with saving his life.
"If I had waited, as the American Cancer Society recommends, until I was 50, I would not have known I had a growing tumor until two years after I got treated," he said in an essay for Medium. "If [my doctor] had followed the U.S. Preventative Services Task Force guidelines, I would have never gotten tested at all, and not have known I had cancer until it was way too late to treat successfully."
"As of this writing," Stiller said, "I am two years cancer free and extremely grateful."
Stiller described the PSA as "a simple, painless blood test" which, in Stiller's case, was ordered as part of his yearly blood work.
"This is a complicated issue, and an evolving one," Stiller said. "But in this imperfect world, I believe the best way to determine a course of action for the most treatable, yet deadly cancer, is to detect it early."