US tycoon Warren Buffett announced on Tuesday that he has early-stage prostate cancer, and indicated he had no intention of stepping down as head of his investment firm Berkshire Hathaway.
Buffett, a larger-than-life financier known as the "Oracle of Omaha" for his investment savvy, said: "I feel great."
With his big glasses and preference for Cherry Coke, Buffett is known for his humble manner and modest tastes despite amassing billions as the mastermind and chief executive of Berkshire.
Buffett held the number three spot on the Forbes richest list released last month, with an estimated net worth of $44 billion.
In a letter to his company's shareholders, released after the stock markets closed, Buffett disclosed he had been diagnosed with Stage 1 prostate cancer last Wednesday and would undergo radiation treatment beginning in mid-July.
Imaging tests revealed no cancer elsewhere in his body, the ebullient 81-year-old investor said.
"The good news is that I've been told by my doctors that my condition is not remotely life-threatening or even debilitating in any meaningful way," he said.
Buffett said that he and his doctors had decided on a two-month treatment of daily radiation, which would restrict his travel "but will not otherwise change my daily routine."
"I feel great -- as if I were in my normal excellent health -- and my energy level is 100%," he said.
The cancer was discovered during a routine medical check-up that showed an unusually large jump in his blood level of prostate-specific antigen (PSA) -- a protein produced by the cells of the prostate.
The prostate is a small gland, the size of a walnut, that is part of the male reproductive system.
"A biopsy seemed warranted," Buffett said.
Prostate cancer is the most frequent cause of death from cancer in men over age 75, according to US official data. But it is relatively slow-growing compared with other forms of cancer.
"I will let shareholders know immediately should my health situation change," Buffett said.
"Eventually, of course, it will; but I believe that day is a long way off," he said.
Berkshire shares rose 1.4% on Tuesday but were down 1.8% in post-market trading.
The question of who will succeed Buffett when the inevitable happens has been gaining intensity as the octogenarian ages.
In February, Buffett announced that a successor had been chosen to lead Berkshire, although he did not identify the person.
"When a transfer of responsibility is required, it will be seamless and Berkshire's prospects will remain bright," Buffett wrote in a letter to investors.
"Do not, however, infer from this discussion that Charlie and I are going anywhere," Buffett said, referring to the firm's vice chairman Charlie Munger, who is 88.
"We continue to be in excellent health and we love what we do."
In December, he said his corn farmer son Howard would be a good "guardian of the culture" at Berkshire, suggesting he could become non-executive chairman -- presiding over the board of directors but not the company itself.
The company's closely watched investment portfolio has significant holdings in the railroad, retail and utility industries.
Buffett recently made headlines by complaining that his secretary paid a higher rate than he did, giving birth to the so-called "Buffett Rule" backed by President Barack Obama.
The initiative calls for a minimum tax rate of 30% for people making more than $1 million a year.
The US Senate blocked the measure on Monday, with Republicans leading the charge and dismissing the bill as a political stunt by Obama's Democratic party.