Actor-filmmaker Ben Stiller revealed on Tuesday that he has survived prostate cancer.

Stiller, 50, star of the “Zoolander” and “Night at the Museum” franchises, said on Howard Stern’s Sirius XM radio show that he was diagnosed with “immediately aggressive” prostate cancer two years ago. “It came out of the blue for me,” Stiller told Stern. “I had no idea.”

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Appearing on the show with his surgeon, Dr. Edward Schaeffer, Stiller advocated for men to have a regular PSA (prostate-specific antigen) blood test. He had done so for two years prior, he said, giving his doctor a baseline from which to track increases in the test numbers.

“I got diagnosed with prostate cancer Friday, June 13th, 2014,” Stiller separately detailed in an essay Tuesday at Medium.com. “On September 17th of that year I got a test back telling me I was cancer free. The three months in between were a crazy roller coaster ride with which about 180,000 men a year in America can identify.”

He said taking the PSA test “saved my life. Literally. . . . There has been a lot of controversy over the test in the last few years. Articles and op-eds on whether it is safe, studies that seem to be interpreted in many different ways, and debates about whether men should take it [at] all. I am not offering a scientific point of view here, just a personal one, based on my experience.”

Though he had no symptoms and was not in a high-risk group genetically, Stiller credits “a thoughtful internist who felt like I was around the age to start checking my PSA level, and discussed it with me. If he 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. If he had followed the US Preventive 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.”