Sir Ian McKellen has revealed that he has been diagnosed with prostate cancer for nearly a decade. 

The seasoned actor said in his interview with the (UK) Mirror before divulging his diagnosis, “You are going to write ‘Ian McKellen is decrepit. He can’t see, he can’t hear he can’t pee, he’s having his teeth done.’”
McKellen said “I’ve had prostate cancer for six or seven years. When you have got it you monitor it and you have to be careful it doesn’t spread. But if it is contained in the prostate it’s no big deal." 
The actor is known for such roles as Erik Lehnsherr/Magneto in the X-Men franchise, and Gandalf the Grey, in the Lord of the Rings franchise.
He has reprised his role as Gandalf the Grey in "The Hobbit: An Unexpected Journey" that will be released Dec. 14. 
McKellen has been extremely busy in several back-to-back roles. He said that he is not currently being treated for the disease, and that the cancer is maintained with frequent testing; however, he does admit that he was concerned during his initial diagnosis.
“You do gulp when you hear the news. It’s like when you go for an HIV test, you go ‘arghhh is this the end of the road?'" he said.
“They come and say you have cancer of the prostate and then they say you can have it zapped, you can have it snipped but you are not a candidate for that. You are waitful watching."
“I have heard of people dying from prostate cancer, and they are the unlucky ones, the people who didn’t know they had got it and it went on the rampage. But at my age if it is diagnosed its not life threatening.”
According to McKellen, he decided to see his doctor when he suddenly needed to make several trips to the bathroom at night. By his own insistence, his doctor gave him a biopsy that discovered the cancer, he said.
Other than a few minor ailments that come with age, the 73-year-old actor said he considers himself in good health, that he maintains himself with regular exercise.
“I just got hearing aids, I am going to have a cataract removed from my eyes, I am having an implant in my mouth, I am dealing with the prostate…I am absolutely fine thank you very much!" he said. 
“I am lucky, I don’t have aches and pains. I do pilates regularly which is a series of stretching exercises and I recommend it to anyone of my age because the temptation is not to exercise when you get older. Well you should."