- Klinefelter's syndrome: This is a fairly rare medical condition that affects approximately one in 1,000 men. Men affected by Klinefelter’s syndrome are known to have an extra X, or female, chromosome and produce unusually high levels of estrogen, a female hormone typically found in men in only very small amounts. Symptoms of Klinefelter’s syndrome include enlarged breasts, small testes, lack of ability to produce sperm, and sparse body or facial hair. Men with this syndrome are 50 times more at risk for male breast cancer than other men.
- Cirrhosis of the liver: This scarring of the liver can be caused by chronic viral hepatitis, genetic conditions or long-term alcohol abuse. Because the liver is responsible for the very important job of producing regulatory proteins that affect hormones in the bloodstream, when it is compromised, it can cause elevated female hormones in the male body and increase the risk of male breast cancer.
- Elevated estrogen levels: Men typically produce minimal amounts of the female hormone estrogen. However, when these levels rise for any reason, it may increase the chance that male breast cancer will develop. Certain medical conditions such as cirrhosis of the liver or Klinefelter’s syndrome are associated with increased breast size and elevated estrogen levels in men, which also may increase the risk of breast cancer. Obesity is also known to raise estrogen levels, as is the use of some medications over a prolonged period.
- Genetic predisposition: There are studies that have shown a link between men with male breast cancer and their female family members who have been diagnosed with breast cancer. There is reason to believe that men who have family members with breast cancer may be at an increased risk of developing this type of cancer. In addition, men may inherit certain mutations in the BRCA-2 gene, which has been associated with an increased risk of developing breast cancer.
- Exposure to radiation: If a man has already been treated for cancer in the chest area via radiation therapy, he may have been placed at an increased risk for breast cancer. Exposure to radiation has been linked to an elevated risk for this type of cancer.
- Medications, particularly Finasteride: Some drugs can cause an elevated risk of cancer in some patients. For example, Finasteride is a drug used to treat conditions including baldness, prostate enlargement and prostate cancer prevention. This link is not yet proven clinically, but there have been more than 50 cases of male breast cancer associated with the use of the drug Finasteride.