Ryan O'Neal is suffering from prostate cancer.

The 70-year-old actor - who has previously battled leukemia - admits he was shocked to discover he had the disease but is expecting to make a full recovery as it was discovered early.

He said in a statement to People.com: ''Recently I was diagnosed with stage four prostate cancer. 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''

Ryan - who lost his partner Farrah Fawcett to anal cancer in 2009 - added he was grateful to his family for their support and urged people to go and get tested for the disease.

He said: ''I am deeply grateful for the support of my friends and family during this time, and I urge everyone to get regular check-ups, as early detection is the best defence against this horrible disease that has afflicted so many.''

Ryan was treated in the late 1990s for leukemia.

He is soon to release a memoir about his life with Farrah entitled 'Both of Us', which is due for release in early May.