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

Breast cancer may occur in men. Breast cancer may occur in men at any age, but it usually occurs 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. This is the most common type of breast cancer in men.
• 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.

A family history of breast cancer and other factors can increase a man's risk of 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. Talk with your doctor if you think you may be at risk. Risk factors for breast cancer in men may include the following:

• Treatment with radiation therapy to your breast/chest.
• Having a disease linked to high levels of estrogen in the body, such as cirrhosis (liver disease) or Klinefelter syndrome (a genetic disorder).
• Having one or more female relatives who have had breast cancer.
• Having mutations (changes) in genes such as BRCA2.

Male breast cancer is sometimes caused by inherited gene mutations (changes).

The genes in cells carry the hereditary information that is received from a person's parents. Hereditary breast cancer makes up about 5% to 10% of all breast cancer. Some mutated genes related to breast cancer, such as BRCA2, are more common in certain ethnic groups. Men who have a mutated gene related to breast cancer have an increased risk of this disease.

There are tests that can detect (find) mutated genes. These genetic tests are sometimes done for members of families with a high risk of cancer. See the following PDQ summaries for more information:

• Genetics of Breast and Gynecologic Cancers
• Breast Cancer Prevention
• Breast Cancer Screening

Men with breast cancer usually have lumps that can be felt.

Lumps and other signs may be caused by male breast cancer or by other conditions. Check with your doctor if you have any of the following:

• A lump or thickening in or near the breast or in the underarm area.
• A change in the size or shape of the breast.
• A dimple or puckering in the skin of the breast.
• A nipple turned inward into the breast.
• Fluid from the nipple, especially if it's bloody.
• Scaly, red, or swollen skin on the breast, nipple, or areola (the dark area of skin around the nipple).
• Dimples in the breast that look like the skin of an orange, called peau d’orange.

Tests that examine the breasts are used to diagnose breast cancer in men.

The following tests and procedures may be used:

• Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Clinical breast exam (CBE): An exam of the breast by a doctor or other health professional. The doctor will carefully feel the breasts and under the arms for lumps or anything else that seems unusual.
• Mammogram: An x-ray of the breast.
• Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of both breasts. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease.
• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. There are four types of biopsies to check for breast cancer:
  • Excisional biopsy: The removal of an entire lump of tissue.
  • Incisional biopsy: The removal of part of a lump or a sample of tissue.
  • Core biopsy: The removal of tissue using a wide needle.
  • Fine-needle aspiration (FNA) biopsy: The removal of tissue or fluid using a thin needle.

If cancer is found, tests are done to study the cancer cells.

Decisions about the best treatment are based on the results of these tests. The tests give information about:

• How quickly the cancer may grow.
• How likely it is that the cancer will spread through the body.
• How well certain treatments might work.
• How likely the cancer is to recur (come back).

Tests include the following:

• Estrogen and progesterone receptor test: A test to measure the amount of estrogen and progesterone (hormones) receptors in cancer tissue. If there are more estrogen and progesterone receptors than normal, the cancer is called estrogen and/or progesterone receptor positive. This type of breast cancer may grow more quickly. The test results show whether treatment to block estrogen and progesterone may stop the cancer from growing.
• HER2 test: A laboratory test to measure how many HER2/neu genes there are and how much HER2/neu protein is made in a sample of tissue. If there are more HER2/neu genes or higher levels of HER2/neu protein than normal, the cancer is called HER2/neu positive. This type of breast cancer may grow more quickly and is more likely to spread to other parts of the body. The cancer may be treated with drugs that target the HER2/neu protein, such as trastuzumab and pertuzumab.

Survival for men with breast cancer is similar to survival for women with breast cancer.

Survival for men with breast cancer is similar to that for women with breast cancer when their stage at diagnosis is the same. Breast cancer in men, however, is often diagnosed at a later stage. Cancer found at a later stage may be less likely to be cured.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis and treatment options depend on the following:

• The stage of the cancer (the size of the tumor and whether it is in the breast only or has spread to lymph nodes or other places in the body).
• The type of breast cancer.
• Estrogen-receptor and progesterone-receptor levels in the tumor tissue.
• Whether the cancer is also found in the other breast.
• The man's age and general health.
• Whether the cancer has just been diagnosed or has recurred (come back).