Less than a few days before the highly anticipated premiere of "The Hobbit," Ian McKellen has revealed that he's been quietly battling prostate cancer for almost a decade.

The 73-year-old, who rose to international fame in both the "X-Men" films and as Gandalf in "The Lord of the Rings," says the diagnosis sounds worse than it is, but nonetheless has rattled his nerves.

“You do gulp when you hear the news," he told The Sun. “It’s like when you go for an HIV test — you go 'Argh, is this the end of the road?’ You monitor it and you have to be careful it doesn’t spread.”

McKellen appears to have a "low-risk localized version" of prostate cancer, often growing so slowly that patients never experience any symptoms.

"Treatments for prostate cancer can cause long-term side effects, so doctors try to avoid giving treatments if they can safely do that," advises the site Cancer Research UK. "If the cancer starts to develop while you are having active monitoring, your doctor will offer you treatment with surgery to remove the prostate gland or radiotherapy to the prostate. You may have hormone therapy before or alongside radiotherapy."

As McKellen tells it, the whole thing is simply a waiting game — and one that hopefully never plays out.

“They say you can have it zapped. You can have it snipped but [if] you’re not a candidate for that, you are ‘waitful watching.’ I am examined regularly and it’s contained. It’s not spreading. I’ve not had any treatment.”

You can see McKellen reprise his role as Gandalf in "The Hobbit: An Unexpected Journey" opening in theaters this weekend. Check out a trailer for the film below.

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Ian McKellen reveals prostate cancer battle
'Hobbit' actor Ian McKellen says he's been carefully monitoring the disease for nearly 7 years.