Male breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.

Breast cancer may occur in men. Men at any age may develop breast cancer, but it is usually detected (found) in men between 60 and 70 years of age. Male breast cancer makes up less than 1% of all cases of breast cancer.

The following types of breast cancer are found in men:

Infiltrating ductal carcinoma: Cancer that has spread beyond the cells lining ducts in the breast. Most men with breast cancer have this type of cancer.
Ductal carcinoma in situ: Abnormal cells that are found in the lining of a duct; also called intraductal carcinoma.
Inflammatory breast cancer: A type of cancer in which the breast looks red and swollen and feels warm.
Paget disease of the nipple: A tumor that has grown from ducts beneath the nipple onto the surface of the nipple.
Lobular carcinoma in situ (abnormal cells found in one of the lobes or sections of the breast), which sometimes occurs in women, has not been seen in men.

Radiation exposure, high levels of estrogen, and a family history of breast cancer can increase a man’s risk of developing breast cancer.

Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Risk factors for breast cancer in men may include the following:

Being exposed to radiation.
Having a disease related to high levels of estrogen in the body, such as cirrhosis (liver disease) or Klinefelter syndrome (a genetic disorder).
Having several female relatives who have had breast cancer, especially relatives who have an alteration of the BRCA2 gene.