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.
Around 3 in 100 breast cancers diagnosed in women (3%) are thought to be due directly to an inherited faulty gene. In men, this may be more common. We think that between 10 and 20 out of every 100 diagnosed in men (10 to 20%) are due to inherited faulty genes.