Breast Cancer in Men
What Are the Risk Factors for Breast Cancer in Men?
A risk factor is anything that increases your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, mouth, larynx, bladder, kidney, and several other organs.
Some men with one or more breast cancer risk factors never develop the disease, while most men with breast cancer have no apparent risk factors. Even when a patient has a risk factor, there is no way to prove that it actually causes the cancer.
Known Risk Factors
Aging: Aging is an important risk factor for the development of breast cancer in men. Men with breast cancer average about 67 years old at the time of their diagnosis.
Family history of breast cancer: Breast cancer risk is increased if other members of the family (”blood relatives”) have had breast cancer. About 20% of men with breast cancer have close male or female relatives with the disease. See the section, “Do We Know What Causes Breast Cancer in Men?” for information on inherited breast cancer genes.
Inherited gene mutations: The gene mutation (change) BRCA2, which is responsible for some breast cancers in women, probably accounts for about 10% of breast cancers in men. BRCA1 mutations can also increase the risk of breast cancer in men but seems to be responsible for fewer cases than the BRCA2 gene. The clue to these mutations would be a strong family history of breast cancer, which often appeared at a young (under 60) age. Other gene mutations that have been thought responsible for some breast cancers in men are mutations in a gene called CHEK2.
Klinefelter syndrome: This is a congenital (present at birth) condition that affects about 1 of 1000 men. Normally men have a single X chromosome along with their Y chromosome, while women have two X chromosomes. Men with this condition have more than one X chromosome (sometimes as many as 4). This causes their testicles to be smaller than usual and not produce functioning sperm cells, making them infertile. Compared with other men, they have lower levels of androgens (male hormones) and more estrogens (female hormones). For this reason, they often develop gynecomastia (benign male breast growth).
Some studies that looked at all men with breast cancer have found more men with Klinefelter syndrome than are found in the normal population. This led doctors to think that breast cancer is a major concern for these men. But this may not be true. One study of 696 Danish men with Klinefelter syndrome found no cases of breast cancer in any of them. One problem is that these are both uncommon problems so that it is hard to collect enough cases to be sure. What this all probably means is that the risk is increased, but it is still very low because this is such an uncommon cancer, even for people with Klinefelter syndrome.
Radiation exposure: A man whose chest area has been exposed to radiation (usually for treatment of a cancer inside the chest, such as Hodgkin or non-Hodgkin lymphoma) has an increased risk of developing breast cancer.
Alcohol: Heavy alcohol intake increases the risk of breast cancer in men.
Liver disease: The liver plays an important role in sex hormone metabolism by producing binding proteins that carry the hormones in the blood. These binding proteins affect the hormones’ activity. Men with severe liver disease such as cirrhosis have relatively low levels of androgen activity and higher estrogen levels. Therefore, they may have an increased risk of developing gynecomastia and breast cancer.
Estrogen treatment: Estrogen-related drugs are sometimes used in hormonal therapy for men with prostate cancer. This treatment may slightly increase their breast cancer risk. However, this risk is small compared with the benefits of this treatment in slowing the growth of prostate cancer. Men taking high doses of estrogens as part of a sex change procedure have a much higher breast cancer risk.
Physical inactivity and obesity: Recent studies have shown that physical activity reduces women’s breast cancer risk and that breast cancer risk is increased by obesity during adult life. Obesity is probably a risk factor for male breast cancer. The reason is that fat cells convert male hormones (androgens) into female hormones (estrogens). This means that obese men have higher levels of estrogens in their body. Some obese men may notice that they don’t have to shave as frequently as other men. They might also have difficulty fathering children because they may be infertile. Regular exercise and maintaining a healthy weight reduces the risk of many diseases and cancers.
Occupation: Some reports have suggested an increased risk in men who work in hot environments such as steel mills. Also, men heavily exposed to gasoline fumes may have a higher risk. Finally, in a study of Florida firefighters there was an excess of breast cancer cases.
