Breast Cancer, Male: Introduction

Aprobado por la Junta Editorial de Cancer.Net, 12/2022

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 Male Breast Cancer. Use the menu to see other pages. Think of that menu as a roadmap for this entire guide.

Male breast cancer, also called breast cancer in men, is rare. It occurs 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 small, 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 the guide to Metastatic Breast Cancer.

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

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. This is uncommon in male breast cancer.

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

  • Lobular carcinoma.This starts in the lobules. It is uncommon in male breast cancer.

    • 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 within 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. Male breast cancer 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 have no HER2 protein are called “HER2 negative.” Cancers that have low levels of the HER2 protein and/or few copies of the HER2 gene are sometimes now called “HER2 low."

  • 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 people 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:

The next section in this guide is Statistics. It helps explain the number of people who are diagnosed with breast cancer and general survival rates. Use the menu to choose a different section to read in this guide.