"Zoolander No. 2" - London Fan ScreeningBen Stiller has revealed that he battled and survived prostate cancer two years ago.

The 50-year-old actor discussed his diagnosis and treatment on Howard Stern's radio show this morning. "It came out of the blue for me. I had no idea," Stiller said, noting he had no family history of the disease.

The "Zoolander 2" star advocated the use of a test that his doctor administered, the Prostate-Specific Antigen (PSA) Test, a simple blood test that he got during a routine physical. Stiller also wrote an essay on Medium, calling it the "Prostate Cancer Test That Saved My Life."

After his diagnosis, Stiller reached out to friends, including "Meet the Parents" co-star Robert De Niro, who had also battled prostate cancer. But he chose not to go public with the news at the time.

"At first, I didn't know what was going to happen. I was scared," he told Stern. "The one thing that it does is it just stops everything in your life when you get diagnosed with cancer because you can't plan for a movie — you don't know what's going to happen."

Now, Stiller is opening up about his cancer battle to help others. Though the PSA test is controversial, he believes it can save lives. As he wrote on Medium, "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."

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