Most breast cancers in men are ductal carcinomas. Ductal means the cancer started in the milk pipes of the breast, called ducts. These cancers are usually invasive because they start inside the duct and then break through the wall of the duct, growing into the normal surrounding breast tissue.
Breast cancer is about 100 times less common among men than among women. For men, the lifetime risk of getting breast cancer is about 1 in 1,000. The number of breast cancer cases in men relative to the population has been fairly stable over the last 30 years.