ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Breast Cancer in Men. Use the menu to see other pages. Think of that menu as a roadmap for this complete guide.
Breast cancer in men is rare, occurring much less often than breast cancer in women. But 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. Tiny ducts connect the glands, lobules, and lobes to the nipple, located in the middle of the areola. The areola 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, which are the small, bean-shaped organs that help fight infection.
About breast cancer
Cancer begins when healthy cells in the breast change and grow out of control, 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.
Although breast cancer most commonly spreads to nearby lymph nodes, it can also spread further through the body to areas such as the bones, lungs, liver, and brain. This is called metastatic or stage IV breast cancer. For more information on this disease, see our Metastatic Breast Cancer guide.
If breast cancer comes back after initial treatment, it can come back in the breast and/or regional lymph nodes, called a local or regional recurrence. It can also recur elsewhere in the body, called a distant recurrence or metastatic recurrence.
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 start in the cells lining the milk ducts. Most breast cancers are ductal carcinomas.
Ductal carcinoma in situ (DCIS). This non-invasive cancer 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 carcinoma.
Lobular carcinoma. This starts in the lobules. It is uncommon in men.
Lobular carcinoma in situ (LCIS). LCIS is located only in the lobules. LCIS is not considered cancer. However, LCIS is a risk factor for developing invasive breast cancer in either breast (see the Risk Factors section for more information).
Invasive lobular carcinoma (ILC). This is cancer that has spread outside the lobules.
Other less common types of breast cancer include:
Breast cancer subtypes
Breast cancer is not a single disease, even among the same type of breast cancer. When you are diagnosed with breast cancer, your doctor will recommend laboratory tests on the cancerous tissue. These tests will help your doctor learn more about the cancer and choose the most effective treatment plan.
Tests can determine if your cancer is:
- Hormone receptor positive or negative. Breast cancers expressing estrogen receptors (ER) and/or progesterone receptors (PR) are called “hormone receptor positive.” These receptors are proteins found in cells. Tumors that have estrogen receptors are called “ER positive.” Tumors that have progesterone receptors are called “PR positive.” These cancers depend on the hormones estrogen and/or progesterone to grow. Breast cancer in men is likely to have receptors for estrogen and progesterone, which means that hormonal therapy is a treatment option for most of these cancers. Breast cancer that does not express estrogen or progesterone receptors is called “hormone receptor negative.”
- HER2 positive or negative. About 10% to 20% of breast cancers depend on the gene called HER2 to grow. These cancers are called “HER2 positive” and have too many 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. Cancers that do not have too much HER2 are called “HER2 negative.”
- Triple negative. If a person’s tumor does not express ER, PR, or HER2, the tumor is called “triple negative.” Triple negative cancers tend to be faster growing cancers. This type of breast cancer may be more common in younger men with breast cancer.
Looking for More of an Introduction?
If you would like more of an introduction, explore these related items. Please note that these links will take you to other sections on Cancer.Net:
- ASCO Answers Fact Sheet: Read a 1-page fact sheet that offers an easy-to-print introduction to breast cancer. This free fact sheet is available as a PDF, so it is easy to print.
- ASCO Answers Guide: Get this free 52-page booklet that helps you better understand this disease and treatment options. The booklet is available as a PDF, so it is easy to print.
- 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.
The next section in this guide is Statistics. It helps explain the number of men who are diagnosed with breast cancer and general survival rates. Use the menu to choose a different section to read in this guide.