The billionaire investor broke the news Friday while speaking to a group of executives from newspapers he owns telling them that he had his 44th and last day of radiation.

Buffett had disclosed in the spring that he had been diagnosed with prostate cancer. At the time, he said the disease was detected early and wasn't life-threatening.

Any discussion of Buffett's health raises inevitable questions about how long he can keep running his investment firm, Berkshire Hathaway. Buffett turned 82 two weeks ago and celebrated by giving away more of his $44 billion fortune to his three children, for their charitable foundations.

(Copyright 2012 by The Associated Press. All Rights Reserved.)