Dense Breasts and Breast Cancer Risk
Dense breast tissue is a strong risk factor for breast cancer. Learn more about why and whether you should be concerned.

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woman thinking and smiling Dense Breasts and Breast Cancer Risk

If you have dense breasts, you may be at higher risk for breast cancer than you think. Breast density is known to be a strong risk factor for breast cancer. It may be almost as important a factor as age.

Breast density is just one of many risk factors for breast cancer. Young women tend to have dense breasts, but this is generally not a concern if they don't have other risk factors. Breast density becomes more of an issue after menopause, when other risk factors such as age, weight and activity level may come into play.

If you don't know if you have dense breasts, ask the next time you have a mammogram. There is not yet a well-defined standard for breast density, but your doctor may be able to help you understand if it is a risk you should take into account.

What is breast density?
Breasts are made up of gland tissue, ligaments and fat. The proportion of these tissues varies among women. Some breasts have a large amount of fatty tissue. Others have mostly gland and connective tissues. This is considered dense tissue because of how it looks on a mammogram.

  • Mammogram x-rays pass through fatty tissue, so it looks black (or clear) in a mammogram.
  • Mammogram x-rays don't penetrate dense tissue, so it looks white in a mammogram.

In general, younger women have denser breasts than older women. The proportion of fatty tissue in the breasts tends to increase with age.

Why are dense breasts a problem?
They are a problem for two reasons:

  • Dense breasts greatly increase the risk of breast cancer. Women with dense breasts are about four to six times more likely to get breast cancer than women with fatty breasts. Experts are not yet sure what accounts for this increased risk, but it seems to be related to the properties of the dense tissue.
  • It's harder to detect breast cancer in dense breasts. Most breast tumors grow as solid masses that show up as white areas on a mammogram. A tumor may be fairly easy to see in breast that is mostly fatty tissue. But a mammogram may not find a tumor in a dense breast, because both the tumor and the dense tissue appear white.

What should a woman with dense breasts do?
Getting regular mammograms is especially important if you have dense breasts. Ask your doctor if you should get a digital mammogram. Compared to the traditional film test, digital mammography seems to be better at finding breast cancer in women who have dense breasts. But it is more expensive, and it's not widely available.

Experts disagree about the best age for women at average risk of breast cancer to start getting mammograms:

  • The American Cancer Society recommends that women have a mammogram and clinical breast exam every year starting at age 40.
  • The U.S. Preventive Services Task Force (USPSTF) suggests that women start having mammograms at age 50 and repeat them every two years. This group also encourages women younger than 50 to talk to their doctor so they can make an informed decision about screening.

These are general recommendations that do not take into account your personal or family medical history. Some women may need to start screening at an earlier age.  

Bottom line:Talk to your doctor about your risk for breast cancer and your personal feelings about screening for this disease. Your doctor can suggest a screening schedule that is right for you.

You can also make efforts to lower your overall cancer risk through healthy choices:

  • Don't smoke. This is the number one way to lower your cancer risk.
  • Stay at a healthy weight. Try to avoid weight gain, especially around your waist.
  • Try to get at least 30 minutes of physical activity every day.
  • Make healthy food choices. Eat plenty of high-fiber, plant-based foods such as whole grains, beans, fruits and vegetables. Limit red meat, saturated fat and salt.
  • If you drink, limit alcohol to no more than one drink a day.
By Lila Havens, Staff Writer
Created on 01/16/2009
Updated on 11/23/2009
  • U.S. Preventive Services Task Force. Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement. Annals of Internal Medicine. 2009;151(10):716-726.
  • National Cancer Institute. Breast density in mammography and cancer risk. NCI Cancer Bulletin. 2008;5(21).
  • Tamimi RM, Byrne C, Colditz GA, Hankinson SE. Endogenous hormone levels, mammographic density, and subsequent risk of breast cancer in postmenopausal women. Journal of the National Cancer Institute. 2007;99(15):1178-1187.
  • Vachon CM, Sellers TA, Carlson EE, et al. Strong evidence of a genetic determinant for mammographic density, a major risk factor for breast cancer. Cancer Research. 2007;67(17):8412-8418.
  • Barlow WE, White E, Ballard-Barbash R, et al. Prospective breast cancer risk prediction model for women undergoing screening mammography. Journal of the National Cancer Institute. 2006;98(17):1204-1214.
Copyright © OptumHealth.
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