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Risk Factors


Lt Col Flemings
A risk factor is something that increases the likelihood of developing a disease. However, it’s important to remember that risk factors are not causes. Some women with many risk factors will never develop breast cancer, and others who have no known risk factors will develop the condition. Major Spencer, will you tell us about some of these risk factors?

Maj Spencer
Absolutely, Dr. Flemings. Age and gender are the two strongest risk factors. Most breast cancers are found in women who are 50 or older.

Other risk factors include:

  • Genetics: Women who have inherited mutations to the BRCA1 and BRCA2 genes are at much higher risk for developing breast cancer, but these mutations occur in a small percentage of the population. About 12 percent of women in the general population will develop breast cancer sometime during their lives. By contrast, it’s estimated that 55 to 65 percent of women who inherit a BRCA1 mutation and 45 percent who inherit a BRCA2 mutation will develop breast cancer by the time they are 70 years old. DNA from a blood or saliva sample is used to test for these mutations.
  • Early menstrual period: Women who start their periods before age 12 are exposed to hormones for a longer time, which raises the risk of breast cancer slightly.
  • Late menopause: Like women who start their periods early, women who start menopause after age 55 are exposed to hormones longer, which can increase the risk of breast cancer.
  • Late or no full-term pregnancy: Women who have their first child after age 30 or who never have children are at higher risk for breast cancer.
  • Physical inactivity: Being physically inactive raises the risk of breast cancer.
  • Obesity after menopause: Breast cancer is more common in older women who are overweight or obese.
  • Dense breasts: Women with dense breasts have more connective tissue than fatty tissue. Dense breasts not only increase the risk of breast cancer, but they can also make it difficult to see tumors on a mammogram.
  • Combination hormone replacement therapy: Taking estrogen and progestin together to replace missing hormones in menopause for more than five years may raise the risk for breast cancer.
  • Oral contraceptives: Some studies suggest that certain birth control pills may increase the risk of breast cancer, but other studies have found the risk increase to be statistically insignificant.
  • Personal history of breast cancer: Women who have had breast cancer once are more likely to get it a second time.
  • Personal history of certain non-cancerous breast diseases: Some benign breast diseases, such as atypical hyperplasia or lobular carcinoma in situ, are associated with a higher risk of breast cancer.
  • Family history of breast cancer: Having a first-degree relative, such as a mother, sister, daughter, or multiple family members with breast cancer increases a woman’s risk.
  • Previous treatment using radiation therapy: Women who have had radiation therapy to the chest or breasts before age 30 – for example, to treat Hodgkin’s lymphoma –have a higher risk of developing breast cancer later in life.
  • Diethylstilbestrol, or DES: DES is a drug that was given to some pregnant women in the United States between 1940 and 1971 to prevent miscarriage. Women who took DES and women whose mothers took DES while pregnant with them are at higher risk for breast cancer.
  • Alcohol: A woman’s risk for breast cancer increases with the amount of alcohol she drinks, and
  • Race: White women are more likely to develop breast cancer than other races.

Although many of the known risk factors can be avoided, others like genetics, family history, and race, cannot. Obviously, it’s very important for women to avoid known risk factors whenever possible. If you think you may be at risk, you should discuss this concern with your provider. Your provider may be able to suggest ways to reduce your risk. They can also work with you to develop an appropriate schedule of physical exams and, in some cases, mammograms.



You can use the Breast Cancer Risk Assessment Tool on the National Cancer Institute website to calculate your risk of developing breast cancer.