Even though men do not have breasts like women, they do have a small amount of breast tissue. In fact the "breasts" of an adult man are similar to the breasts of a girl before puberty, and consist of a few ducts surrounded by breast and other tissue. In girls, this tissue grows and develops in response to female hormones, but in men -- who do not secrete the same amounts of these hormones -- this tissue does not develop.

However, because it is still breast tissue, men can develop breast cancer. In fact, men get the same types of breast cancers that women do, although cancers involving the milk producing and storing regions of the breast are very rare.

Breast cancer in men is a very rare disease. This is possibly due to their smaller amount of breast tissue and the fact that men produce smaller amounts of hormones like estrogen that are known to affect breast cancers in women.

In fact, only about 1 in 100 breast cancers affect men and only about 10 men in a million will develop breast cancer.

It is very rare for a man under age 35 to get breast cancer, but the likelihood of developing the disease increases with age. Beyond that, African-American men appear to be at greater risk than white men. In fact, in some places in Africa breast cancer in men is much more common. Also, college-educated professionals appear to have a higher risk than the general male population.

The clearest risk for developing breast cancer seems to be in men who have had an abnormal enlargement of their breasts (called gynecomastia) in response to drug or hormone treatments, or even some infections and poisons. Individuals with a rare genetic disease called Klinefelter's syndrome, who often have gynecomastia as part of the syndrome, are especially prone to develop breast cancer.

How serious is breast cancer in men?

Doctors used to think that breast cancer in men was a more severe disease than it was in women, but it now seems that for comparably advanced breast cancers, men and women have similar outcomes.

The major problem is that breast cancer in men is often diagnosed later than breast cancer in women. This may be because men are less likely to be suspicious of an abnormality in that area. In addition, their small amount of breast tissue is harder to feel -- making it more difficult to catch these cancers early, and allowing tumors to spread more quickly to the surrounding tissues.

What are the symptoms of breast cancer in men?

Symptoms are very similar to those in women. Most male breast cancers are diagnosed when a man discovers a lump on his chest. However, unlike women, men tend to go to the doctor with more severe symptoms that often include bleeding from the nipple and abnormalities in the skin above the cancer. The cancer has already spread to the lymph nodes in a large number of these men.

The same techniques -- physical exams, mammograms, and biopsies (examining small samples of the tissue under a microscope) -- that are used to diagnose breast cancer in women are also used in men.

The same four treatments that are used in treating breast cancer in women -- surgery, radiation, chemotherapy, and hormones -- are also used to treat the disease in men. The one major difference is that men with breast cancer respond much better to hormone treatments than women do. As discussed in the section on breast cancer in women, many breast cancers have hormone receptors, that is, they have specific sites on the cancer cells where specific hormones like estrogen can act.

Men are much more likely to have these receptors than women, making hormonal treatment more likely to be effective.