(Reuters) - Actor and director Ben Stiller said on Tuesday that he had been diagnosed with prostate cancer two years ago, and said a controversial early screening test had saved his life.

The "Zoolander" star, 50, said he was diagnosed in June 2014 and that after surgery he was declared cancer free three months later.

"So, I had cancer a couple of years ago and I wanted to talk about it. And the test that saved my life," tweeted Stiller linking to an essay on Medium.com about his experience.

He described the three months between his diagnosis and treatment as "a crazy roller coaster ride with which about 180,000 men a year in America can identify."

Stiller said he felt lucky that he had taken an early blood test called the Prostate Specific Antigen (PSA) test, which has proved controversial among the medical profession because it can give false-positive or false-negative results and lead to invasive treatment.

"Taking the PSA test saved my life," wrote Stiller. "Literally. That's why I'm writing this now."

"I am not offering a scientific point of view here, just a personal one, based on my experience," he added.

(Reporting by Melissa Fares in New York; Editing by Jill Serjeant and Lisa Shumaker)