Overview

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

The breast is mainly composed 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 (darker area that surrounds the nipple of the breast). Blood and lymph vessels 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 tiny, bean-shaped organs that normally help fight infection.

The main types of breast cancer are the same for men and women. About 90% of all breast cancer cases start in the ducts or lobes. Almost 75% of all breast cancers begin in the cells lining the milk ducts and are called ductal carcinomas. Approximately 30% of male breast cancers are lobular carcinoma (cancer that begins in the lobules) that is found in both breasts.

A type of breast cancer that has spread outside of the duct and into the surrounding tissue is called invasive or infiltrating ductal carcinoma (IDC). The majority of male breast cancer cases are IDC. If the cancer begins at the end of the ducts, it is called infiltrating lobular carcinoma, a rare type of breast cancer.

Disease that has not spread is called in situ, meaning "in place." The course of in situ disease, as well as its treatment, depends on where in the breast the cancer started. Currently, oncologists recommend that ductal carcinoma in situ (DCIS), which accounts for the majority of in situ breast cancers, be surgically removed to help prevent the cancer from spreading to other parts of the breast or the body. DCIS is uncommon in men.

Inflammatory breast cancer makes up about 1% to 5% of all breast cancers. Paget's disease of the nipple begins in the ducts, but spreads to the skin of the nipple. Paget’s disease is more common in men than in women. Other, less common cancers of the breast include medullary, mucinous, tubular, or papillary.

Cancer may begin as a single, genetically abnormal cell. As this one cell divides, it eventually becomes a tumor (a mass of cells) and develops a blood supply to nourish its continued growth. At some point, cells may break off from the primary mass and move to other parts of the body in a process called metastasis.

Breast cancer spreads when breast cancer cells move to other sites in the body through the blood vessels and/or lymph vessels. A common site of spread is the regional lymph nodes. The lymph nodes can be axillary (located under the arm), cervical (located in the neck), or supraclavicular (located just above the collarbone). The most common sites of distant metastasis are the bones, lungs, and liver. Less commonly, breast cancer may spread to the brain. The cancer can also recur (come back after treatment) locally in the skin, in the same breast (if it was not removed as part of treatment), other tissues of the chest, or elsewhere in the body.

Breast cancer in men is detected the same way as breast cancer in women is—through self-examination, clinical examination, or mammography (x-ray of the breast). Changes in the breast may be easier to detect because men have less breast tissue. However, the awareness of breast cancer in men is much lower than it is in women; therefore, men may not perform regular breast self-examinations or talk with their doctor about the disease.

Statistics

In 2009, there will be an estimated 1,910 new cases of breast cancer diagnosed in men in the United States. An estimated 440 men will die of breast cancer this year.

Breast cancer in men and women has similar survival rates. For the earliest stages of breast cancer, stages 0 and I, the five-year relative survival rate (the percentage of people who survive at least five years after the cancer is detected, excluding those who die from other diseases) is 98%. Survival rates drop as the stages (see Staging) increase. Men with breast cancer that has spread regionally have an 84% five-year relative survival rate, and men with cancer that has spread to other parts of the body have a 27% five-year survival rate. Even if the cancer is found at a more advanced stage, new therapies enable many people with breast cancer to experience the same quality of life as before their diagnosis.

Cancer survival statistics should be interpreted with caution. These estimates are based on data from thousands of cases of this type of cancer in the United States each year, but the actual risk for a particular individual may differ. It is not possible to tell a man how long he will live with breast cancer. Because the survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer.

Statistics adapted from the American Cancer Society's publication, Cancer Facts & Figures 2009.

Find out more about basic cancer terms used in this section.