Risk Factors for Breast Cancer

The main factors that influence your risk for breast cancer include being a woman, being older (most breast cancers are found in women who are 50 years old or older), and having changes in certain breast cancer genes (BRCA1 and BRCA2). In addition, studies have shown that some other factors may also influence your risk.

Factors That Decrease Your Risk

  • Being older when you first had your menstrual period.

  • Starting menopause at an earlier age.

  • Giving birth to more children, being younger at the birth of your first child, and breastfeeding your children.

  • Getting regular exercise.

  • Maintaining a healthy weight.

Factors That Increase Your Risk

  • Long-term use of hormone replacement therapy.

  • Personal history of breast cancer or non-cancerous breast diseases.

  • Family history of breast cancer (on either your mother’s or father’s side of the family).

  • Treatment with radiation therapy to the breast/chest.

  • Exposure to diethylstilbestrol (DES) (for example, if you took DES during pregnancy or your mother took DES during her pregnancy with you).

  • Dense breasts by mammogram.

  • Drinking alcohol.

  • Night-shift work.

Some women will develop breast cancer even without any known risk factors. Having a risk factor does not mean you will get the disease, and not all risk factors affect your risk to the same extent. Most women have some risk factors and most women do not get breast cancer. If you have breast cancer risk factors, talk with your doctor about ways you can lower your risk and about screening for breast cancer.