Breast Cancer in Men

Breast cancer in men is rare, accounting for less than 1% of all breast cancers. Although breast cancer in men occurs much less often than breast cancer in women, the diseases are similar in many ways.

About the breast

The breast is mostly made up of fatty tissue. Within this tissue is a network of lobes, which are made up of tiny, tube-like structures called lobules that contain milk glands. Tiny ducts connect the glands, lobules, and lobes to the nipple, located in the middle of the areola, which is the darker area that surrounds the nipple. Blood and lymph vessels also run throughout the breast; blood nourishes the cells, and the lymph system drains bodily waste products. The lymph vessels connect to lymph nodes, the tiny, bean-shaped organs that help fight infection.

About breast cancer

Cancer begins when healthy cells in the breast change and grow uncontrollably, forming a mass or sheet of cells called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread.

Breast cancer spreads when the cancer grows into other parts of the body or when breast cancer cells move to other parts of the body through the blood vessels and/or lymph vessels. This is called metastasis. Breast cancer most commonly spreads to the regional lymph nodes. The regional lymph nodes are located under the arm, in the neck, under the chest bone, or just above the collarbone. When the cancer spreads further through the body, it most commonly spreads to the bones, lungs, and liver. Less often, breast cancer may spread to the brain. If cancer comes back after initial treatment, it can recur locally, meaning in the breast and/or regional lymph nodes. It can also recur elsewhere in the body, called distant metastases.

Types of breast cancer

The main types of breast cancer are the same for men and women. Most breast cancers start in the ducts or lobes and are called ductal carcinomas or lobular carcinomas:

  • Ductal carcinoma. These cancers starts in the cells lining the milk ducts and make up the majority of breast cancers.

    • Ductal carcinoma in situ (DCIS). This is cancer that is located only in the duct. It is uncommon in men.

    • Invasive or infiltrating ductal carcinoma (IDC). This is cancer that has spread outside of the duct. Most men with breast cancer have invasive ductal carcinomas.

  • Lobular carcinoma.This starts in the lobules.

    • Lobular carcinoma in situ (LCIS). LCIS is located only in the lobules. LCIS is not considered cancer. However, LCIS in one breast is a risk factor for developing invasive breast cancer in both breasts (see the Risk Factors section for more information.)

    • Invasive lobular carcinoma (ILC). This is cancer that has spread outside the lobule.

Other, less common types of breast cancer include:

  • Medullary

  • Mucinous

  • Tubular

  • Metaplastic

  • Papillary breast cancer

  • Inflammatory breast cancer is a faster-growing type of cancer that accounts for about 1% to 5% of all breast cancers. However, it is uncommon in men.

  • Paget’s disease is a type of cancer that begins in the ducts of the nipple. Although it is usually in situ, it can also be an invasive cancer. It is more common in men than in women.

Breast cancer subtypes

Breast cancer is not all one disease, even among the same type of breast cancer. Often, the disease is made up of three main subtypes. Special receptors on the outside of the cancer cell help determine the subtype of breast cancer:

  • Hormone receptor positive. Breast cancers expressing estrogen receptors (ER) and progesterone receptors (PR) are called hormone receptor positive. These cancers may depend on the hormones estrogen and/or progesterone to grow. Breast cancer in men is more likely to have receptors for estrogen and progesterone, which means that hormonal therapy is an option for these cancers.

  • HER2 positive. About 20% to 25% of breast cancers depend on the gene called human epidermal growth factor receptor 2 (HER2) to grow. These cancers are called HER2 positive and have excessive numbers of HER2 receptors or copies of the HER2 gene. The HER2 gene makes a protein that is found on the cancer cell and is important for tumor cell growth. This type of cancer may grow more quickly.

  • Triple negative. If a person’s tumor does not express ER, PR, and/or HER2, the tumor is called triple-negative. Triple negative cancers tend to be faster growing cancers. This category of breast cancer may be more common in younger men diagnosed with breast cancer.

Looking for More of an Overview?

If you would like additional introductory information, explore these related items. Please note these links will take you to other sections on Cancer.Net:

  • ASCO Answers Fact Sheet: Read a one-page fact sheet (available as a PDF) that offers an easy-to-print introduction to breast cancer.

  • ASCO Answers Guide: This 52-page booklet (available as a PDF) helps newly diagnosed patients better understand their disease and treatment options, as well as keep track of the specifics of their individual cancer care plan.

  • Cancer.Net Patient Education Video: View a short video led by an ASCO expert in breast cancer that provides basic information and areas of research.