Bob Moon: Billionaire investing legend Warren Buffett has been diagnosed with early-stage prostate cancer. The CEO and chairman of Berkshire Hathaway is assuring shareholders his disease is not life threatening.

But John Dimsdale reports the diagnosis is a reminder the “Oracle of Omaha” is growing older.

John Dimsdale: Buffett is 81, and has already told shareholders succession plans are in place. He’ll begin radiation treatment five days a week for six weeks. But he says he feels great, still has lots of energy and has no plan to retire any time soon.

David Kass at the University of Maryland business school doesn’t think he has to.

David Kass: His typical workday is sitting in his office reading annual reports and maybe speaking on telephone. I think those responsibilities would be easily maintained. So I really don’t think this should have a major influence on his performance.

Last February, Buffett told investors Berkshire Hathaway’s board has chosen someone to takeover as CEO when he does retire, and he says there are two backup candidates. Not one of the three has been identified.

In Washington, I’m John Dimsdale for Marketplace.