When statistics are adjusted for factors such as age, the men with breast cancer are less likely to die from the disease than women.
Researchers had earlier assumed breast cancer was deadlier for males.
The American Cancer Society estimates that 2,000 men in the United States will develop breast cancer this year and about 450 men will die from it.
Experts say the lifetime risk that a man will develop breast cancer is one in 1,000. The chances increase about 7 percent if a man has a mutation in a gene known as BRCA2. The same mutation greatly boosts the risk of breast cancer in women.