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 a rare disease in men. Germ-line mutations in BRCA2 and androgen receptor (AR) genes are thought to be responsible for a proportion of male breast cancer cases. The results of this study suggest that germ-line BRCA2 mutations account for rather small proportion of male breast cancer in Poland.