Prevention & Early Detection

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Breast Cancer Risk Factors

Doctors don’t know why one woman gets breast cancer and another doesn’t, but there are some things you can do to reduce your risk and help make sure that any cancer can be detected early. Some of the most common risk factors for breast cancer are described below. Even if you have several of these factors, you may not develop breast cancer.

To estimate your own risk for developing invasive breast cancer, use the interactive Breast Cancer Risk Assessment Tool developed by scientists at the National Cancer Institute and the National Surgical Adjuvant Breast and Bowel Project.

Risk Factors You Can’t Change

  • Gender: Breast cancer is far more prevalent among women than men.
  • Age: The risk of developing breast cancer increases as you age.
  • Menstrual periods: Your risk increases if you began menstruating before age 12 or reached menopause after age 55.
  • Personal history of breast cancer: If you’ve already had breast cancer, you’re at increased risk of getting another tumor in either breast.
  • Family history of breast cancer: If your mother, daughter, or sister has had breast cancer, you are at greater risk. However, most women who are diagnosed with breast cancer do not have a family history of the disease.
  • Genetics: About 5 to 10 percent of breast cancer cases are related to genetic mutations that are inherited from a parent. The most common genetic mutations are in the BRCA1 and BRCA2 genes, which can increase breast cancer risk in both women and men, with lifetime breast cancer risk in the range of 45 to 65 percent. Careful analysis of breast and ovarian cancer patterns in your family can help identify individuals at risk for hereditary breast cancer.
  • Dense Breasts: Breasts are made of different types of tissue–fatty, fibrous, and glandular tissue. Your breasts are considered dense if you have more fibrous or glandular tissue on mammography compared to the amount of fatty tissue. Dense breast tissue can make it more difficult for doctors to spot cancer on a mammogram, and may also increase your risk for developing breast cancer, but breast density only has a small impact on your overall risk for developing the disease.
  • Race and ethnicity: White women are slightly more likely to develop breast cancer than are African-American women, although African-American women are more likely to die of this cancer. Asian, Hispanic, and Native American women have a lower risk for getting breast cancer.
  • Previous radiation therapy: You are at significantly increased risk for breast cancer if you are a woman who had radiation therapy for another cancer, such as Hodgkin's disease, when you were a child or young adult.

Lifestyle Risk Factors

  • Delayed childbirth: Your risk increases if you never gave birth or if you had your first child after age 30.
  • Hormone replacement therapy: Studies have shown a link between taking long-term hormone replacement therapy and developing breast cancer.
  • Alcohol: Drinking alcohol is linked to an increased risk of developing breast cancer. The more alcohol consumed, the greater the risk.
  • Overweight: Being overweight or obese has been found to increase breast cancer risk, especially for postmenopausal women.

Breast Cancer Risk Assessment Tool

Understand your risk for developing breast cancer with this interactive tool designed by scientists at the National Cancer Institute (NCI) and the National Surgical Adjuvant Breast and Bowel Project (NSABP).