Few people realize that men can develop breast cancer. Nearly 2,000 men are expected to be diagnosed in 2007, according to the American Cancer Society (ACS). This compares to the ACS‘s 2007 estimates of 178,000 new cases of breast cancer diagnosed in women.

In the United States, an estimated 41,000 women and 450 men will die from breast cancer in 2007. Male breast cancer accounts for less than 1 percent of all breast cancer diagnoses and less than 1 percent of cancers in men.

The incidence rate of breast cancer among men has been rising. Between 1975 and 2002, the rate increased by 1.1. percent annually. Researchers are unsure of the reasons for the increase, although it is not attributed to increased detection. In the past, breast cancer was not typically diagnosed in men until it reached the later stages. However, this trend appears to no longer be the case. Mortality rates for men with breast cancer have stayed essentially the same since 1975. When comparing survival rates, men and women with the same stage of breast cancer have a similar prognosis.

The body’s organs and glands (including breasts) are made up of tissues composed of cells. Normal cells grow, divide and die when they grow old, allowing for new cells to take their place. When old cells do not die and the body continues to create new cells it does not need, a mass of cells forms a growth or tumor.

Tumors do not always signal cancer, particularly in the male breast. They can be benign (noncancerous) or malignant (cancerous). The most common breast disorder in men is gynecomastia, a nontumorous growth of tissue caused by hormonal changes. This condition can be mistaken for a tumor. Papillomas and fibroadenomas are benign tumors that are common in women, but extremely rare in men.

During puberty, a girl’s ovaries produce hormones that cause the breasts to grow. When boys enter puberty, the testicles produce male hormones that prevent the breasts from growing. Men have breast tissue, which contain breast ducts but few or none of the milk-producing glands (lobules) found in women.

Breast cancer begins with an abnormal growth of cells within the breast. The type of breast cancer is diagnosed by determining if the cancer began in the ducts, lobules or other area, such as the connective tissue. In some uncommon cases, cancer can develop from the blood vessels. It is also important to determine if the cancer has been contained in the original site or spread to nearby tissues or lymph nodes.

The lymph nodes are bean-shaped structures that are part of the immune system. They help the body fight off infections and diseases. When breast cancer starts to spread, the most common first location is the lymph nodes. If breast cancer has spread to the axillary lymph nodes (located in the underarm region), it can cause swelling of these nodes. 

After the cancer cells have spread to the lymph nodes, if it remains undetected, it is likely that the cancer will spread or metastasize to other areas as well, such as the lungs, bones or brain. It is important to determine if cancer has spread to the lymph nodes for treatment planning and to help determine a patient's outlook for survival.