It's important to understand the risk factors for male breast cancer — particularly because men are not routinely screened for the disease and don't think about the possibility that they'll get it. As a result, breast cancer tends to be more advanced in men than in women when it is first detected.
A number of factors can increase a man's risk of getting breast cancer:
- Growing older: This is the biggest factor. Just as is the case for women, risk increases as age increases. The median age of men diagnosed with breast cancer is about 67. This means that half the men who are diagnosed are over 67 and half are under.
High estrogen levels: Breast cell growth — both normal and abnormal — is stimulated by the presence of estrogen. Men can have high estrogen levels as a result of:
- taking hormonal medicines
- being overweight, which increases the production of estrogen
- having been exposed to estrogens in the environment (such as estrogen and other hormones fed to fatten up beef cattle, or the breakdown products of the pesticide DDT, which can mimic the effects of estrogen in the body)
- being heavy users of alcohol, which can limit the liver's ability to regulate blood estrogen levels
- having liver disease, which usually leads to lower levels of androgens (male hormones) and higher levels of estrogen (female hormones). This increases the risk of developing gynecomastia (breast tissue growth that is non-cancerous) as well as breast cancer.
- Klinefelter syndrome: Men with Klinefelter syndrome have lower levels of androgens (male hormones) and higher levels of estrogen (female hormones). Therefore, they have a higher risk of developing gynecomastia (breast tissue growth that is non-cancerous) and breast cancer. Klinefelter syndrome is a condition present at birth that affects about 1 in 1,000 men. Normally men have a single X and single Y chromosome. Men with Klinefelter syndrome have more than one X chromosome (sometimes as many as four). Symptoms of Klinefelter syndrome include having longer legs, a higher voice, and a thinner beard than average men; having smaller than normal testicles; and being infertile (unable to produce sperm).
- A strong family history of breast cancer or genetic alterations: Family history can increase the risk of breast cancer in men — particularly if other men in the family have had breast cancer. The risk is also higher if there is a proven breast cancer gene abnormality in the family. Men who inherit abnormal BRCA1 or BRCA2 genes (BR stands for BReast, and CA stands for CAncer) have an increased risk for male breast cancer. This risk of developing breast cancer by age 70 is approximately 1% with the BRCA1 gene and 6% with the BRCA2 gene. Overall, that's about 80 times greater than the lifetime risk of men without BRCA1 or BRCA2 abnormalities. Also, a family in which male breast cancer has occurred has a 60% to 76% risk of having an abnormal BRCA2 gene. An abnormal BRCA2 gene accounts for up to 40% of male breast cancers. Because of this strong association between male breast cancer and an abnormal BRCA2 gene, first-degree relatives (siblings, parents, and children) of a man diagnosed with breast cancer may want to ask their doctors about genetic testing for abnormal breast cancer genes. Still, the majority of male breast cancers happen in men who have no family history of breast cancer and no inherited gene abnormality.
- Radiation exposure: Having radiation therapy to the chest before age 30, and particularly during adolescence, may increase the risk of developing breast cancer. This has been seen in young people receiving radiation to treat Hodgkin's disease. (This does NOT include radiation therapy to treat breast cancer.)