Ryan O'Neal is suffering from stage 4 prostate cancer.
The actor, 70, who previously battled leukemia, made the revelation Friday night.
"Although I was shocked and stunned by the news, I feel fortunate that it was detected early and according to my extraordinary team of doctors the prognosis is positive for a full recovery," O'Neal told People.
O'Neal, who lost his longtime love Farrah Fawcett to cancer three years ago, has a book coming out about their years together. Both of Us hits stores May 1.