The actor, who was diagnosed with the condition back in 2018, revealed that she believes the stress of working was responsible.
In an interview with The Times, Walters said: “The oncologist said to me, ‘What do you think has caused the cancer?’ And the first thing that came to my mind was acting.
“Acting caused it, because of the way I approach it — I have to be totally in it. It’s very stressful. You’re being judged. It’s a stressful job and I don’t sleep when I’m working. It’s not good for me.”
Though the Educating Rita star said that she would be quitting acting for good as a result, she did cite one role for which she would be willing to make an exception.
“I don’t want to work again,” she said. “Unless it’s another Mamma Mia.”
In Mamma Mia! (2008), and its 2018 sequel, Mamma Mia! Here We Go Again! Walters played Rosie, a former bandmate of Meryl Streep’s Donna.
Last year, it was revealed that Walters was in remission, having undergone treatment for bowel cancer for around a year and a half.