© 2005-2012 American Society of Clinical Oncology (ASCO). All rights reserved worldwide.
A risk factor is anything that increases a person's chance of developing cancer. Although risk factors can influence cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. However, knowing your risk factors and communicating them to your doctor can help you make more informed lifestyle and health care choices.
The following factors can raise a man's risk of breast cancer:
Family history of breast disease or presence of a genetic mutation. About 20% of breast cancers in men occur in those who have a family history of the disease. Men with breast cancer gene 2 (BRCA2) gene mutations may be at increased risk for breast cancer or other types of cancer. Learn more about the genetics of breast cancer.
Age. The average age for men to be diagnosed with breast cancer is 65.
Elevated estrogen levels. The presence of certain diseases, conditions, or treatments can increase estrogen (female hormones) levels.
- Klinefelter's syndrome, a genetic condition in which men are born with an extra X chromosome, may increase the risk of male breast cancer because men with Klinefelter's syndrome have higher levels of estrogens and lower levels of androgens (male hormones).
- Liver disease, such as cirrhosis, can disrupt hormone levels and cause low levels of androgens and higher levels of estrogens.
- Low doses of estrogen-related drugs that are given for the treatment of prostate cancer may slightly increase the risk of breast cancer.
Radiation. High doses of radiation may increase the risk of breast cancer. An increased risk of breast cancer has been observed in long-term survivors of atomic bombs, people with lymphoma treated with radiation therapy to the chest, people undergoing large numbers of x-rays (such as for tuberculosis or to treat residual thymic disease or acne), non-cancerous conditions of the spine, and children treated with radiation therapy for ringworm.
Lifestyle factors. As with other types of cancer, studies continue to show that various lifestyle factors may contribute to the development of breast cancer.
- Being obese or even overweight increases the risk of breast cancer.
- Increased physical activity is associated with decreased breast cancer risk. This may be because exercise lowers hormone levels, boosts the immune system, and changes metabolism. Lack of exercise also contributes to obesity.
- Drinking more than one alcoholic drink per day may raise the risk of breast cancer.
Currently, there is no proven method for preventing male breast cancer. A person's best chance of surviving breast cancer is early detection through regular self-examinations, clinical breast examinations (breast exam performed by a doctor or other health care professional), and mammography (an x-ray of the breast). Men should be familiar with the feel of their breast tissue normally, so they can bring any lump or change to their doctor's attention. During an annual physical examination, the health care professional will perform a clinical examination of the breast. Mammograms are not routinely offered to men and may be difficult to perform because of the small amount of breast tissue. A doctor may recommend regular mammography for men with a strong family history of breast cancer or the presence of a genetic mutation that increases their risk of developing the disease.