The screen legend, 73, prompted fears for his health earlier this week (begs10Dec12) when editors at Britain's Daily Mirror newspaper published quotes about his secret cancer crisis.
He told the paper, "You do gulp when you hear the news... I've had it 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... I am examined regularly and it's just contained, it's not spreading. I've not had any treatment."
His agent Chris Andrews promptly dismissed the cancer talk on Tuesday (11Dec12), insisting the quotes were old and claiming his star client had been misinterpreted, telling ABCNews.com, "No, he does not have prostate cancer. That was taken out of context and from an interview from years ago."
However, Andrews may need to check his facts - because McKellen himself addressed speculation about his health in a Twitter.com post on Wednesday (12Dec12), confirming that doctors have found cancerous cells in his prostate, but insisting it is nothing to worry about.
He writes, "There have been new reports in the press of the old news that I have early prostate cancer. This was diagnosed six or seven years ago. There is no cause for alarm. I am examined regularly and the cancer is contained. I've not needed any treatment."
McKellen has certainly not shown any signs of illness - he has been busy promoting his new film, The Hobbit: An Unexpected Journey, in recent weeks and he appeared in high spirits as he walked the red carpet at the most recent premiere in New York last week (06Dec12).