A breast cancer risk factor is anything that makes it more likely you'll get breast cancer. But having one or even several breast cancer risk factors doesn't necessarily mean you'll develop breast cancer. Many women who develop breast cancer have no known risk factors other than simply being women.

Factors that are associated with an increased risk of breast cancer include:

  • Being female. Women are much more likely than men are to develop breast cancer.
  • Increasing age. Your risk of breast cancer increases as you age.
  • A personal history of breast cancer. If you've had breast cancer in one breast, you have an increased risk of developing cancer in the other breast.
  • A family history of breast cancer. If your mother, sister or daughter was diagnosed with breast cancer, particularly at a young age, your risk of breast cancer is increased. Still, the majority of people diagnosed with breast cancer have no family history of the disease.
  • Inherited genes that increase cancer risk. Certain gene mutations that increase the risk of breast cancer can be passed from parents to children. The most common gene mutations are referred to as BRCA1 and BRCA2. These genes can greatly increase your risk of breast cancer and other cancers, but they don't make cancer inevitable.
  • Radiation exposure. If you received radiation treatments to your chest as a child or young adult, your risk of breast cancer is increased.
  • Obesity. Being obese increases your risk of breast cancer.
  • Beginning your period at a younger age. Beginning your period before age 12 increases your risk of breast cancer.
  • Beginning menopause at an older age. If you began menopause at an older age, you're more likely to develop breast cancer.
  • Having your first child at an older age. Women who give birth to their first child after age 35 may have an increased risk of breast cancer.
  • Having never been pregnant. Women who have never been pregnant have a greater risk of breast cancer than do women who have had one or more pregnancies.
  • Postmenopausal hormone therapy. Women who take hormone therapy medications that combine estrogen and progesterone to treat the signs and symptoms of menopause have an increased risk of breast cancer. The risk of breast cancer decreases when women stop taking these medications.
  • Drinking alcohol. Drinking alcohol increases the risk of breast cancer.
May. 22, 2013