The 75-year-old star released a statement about his health to People, revealing he was undergoing treatment for the illness.
“I have always been open about the way in which I conduct my life and in that spirit I would like to make a statement. I have recently been diagnosed with early stage pancreatic cancer,” the statement read.
“I am undergoing treatment and am more than optimistic about a satisfactory outcome, as indeed is the medical team.
“I am continuing to focus on my professional commitments and will shortly be recording ‘Jeffrey Bernard Is Unwell (one of life’s small ironies!) for BBC Radio 4,” the statement finished.
Sir John received a knighthood from Queen Elizabeth in December for his services to drama. He has enjoyed a long career in the arts with memorable roles in the films Midnight Express, The Elephant Man (both Oscar-nominated parts), The Naked Civil Servant, Alien and the Harry Potter series.