Factors that increase the risk of male breast cancer include:

  • Older age. Your risk of male breast cancer increases as you age. The peak incidence of male breast cancer occurs between the ages of 68 and 71.
  • Exposure to estrogen. If you take estrogen-related drugs, such as those used as part of a sex-change procedure or for hormone therapy for prostate cancer, your risk of breast cancer is increased.
  • Family history of breast cancer. If you have a close family member with breast cancer, you have a greater chance of developing the disease.
  • Klinefelter’s syndrome. This genetic syndrome occurs when a boy is born with more than one copy of the X chromosome. Klinefelter’s syndrome causes abnormal development of the testicles. As a result, men with this syndrome produce lower levels of certain male hormones (androgens) and more female hormones (estrogens).
  • Liver disease. Certain conditions, such as cirrhosis of the liver, can reduce male hormones and increase female hormones, increasing your risk of breast cancer.
  • Fat cells convert androgens into estrogen. A higher number of fat cells in your body may result in increased estrogen and higher risk of breast cancer.
  • Radiation exposure. If you’ve received radiation treatments to your chest, such as those used to treat cancers in the chest, you’re more likely to develop breast cancer later in life.
  • Testicle disease or surgery. Having inflamed testicles (orchitis) or surgery to remove a testicle (orchiectomy) can increase your risk of male breast cancer.