People magazine reports on its website Wednesday that the 73-year-old actress received the news on Jan. 15. The report says she has as little as three months to live.
Harper tells the magazine in a cover interview: "I don't think of dying. I think of being here now."
Harper's character, Rhoda, was one of television's most beloved sidekicks during the 1970s.
The Associated Press was trying to reach a representative for Harper.