Billionaire investor Warren Buffett has completed radiation treatment for prostate cancer, according to a newspaper owned by the larger-than-life financier. \"It\'s a great day for me. Today I had my 44th and last day of radiation,\" the tycoon told executives of newspapers he recently acquired on Friday, according to a report on the website of The Omaha World-Herald. Buffett -- known for his humble manner and modest tastes despite amassing billions as the mastermind and chief executive of investment firm Berkshire Hathaway -- had announced in April that he had an early stage of the cancer and would undergo treatment. \"I\'ll be feeling the side effects for a few weeks yet, but I am so glad to say that\'s over,\" The Omaha World-Herald quoted the 82-year-old as saying. The Omaha World-Herald Company is owned by Berkshire Hathaway. Buffett held the number three spot on the Forbes richest list released earlier this year, with an estimated net worth of $44 billion. Prostate cancer is the most frequent cause of death from cancer in men over 75 years old, according to US official data. But it is relatively slow-growing compared with other forms of cancer.