I've read that a mammogram is useless when it comes to detecting cancer in women with dense breasts. Is this true?
Answers from Sandhya Pruthi, M.D.
Dense breasts can make mammograms more difficult to interpret. But this doesn't mean a mammogram is useless for detecting cancer or other breast abnormalities in women with dense breasts.
Breast tissue is composed of fatty (nondense) tissue and connective (dense) tissue. Women with dense breasts have more connective tissue than fatty tissue. About half of women undergoing mammograms have dense breasts.
Dense breast tissue appears as a solid white area on a mammogram, and fat appears as a dark area. Mammogram X-rays do not penetrate — or "see through" — dense tissues as well as they do through fat. So, in women with dense breasts, mammograms may be more difficult to interpret.
Some studies have found that newer digital mammography does a better job detecting cancer in dense breasts than does mammography that uses film. A digital mammogram produces images on a computer screen that can be enhanced and magnified for closer viewing. Most mammogram machines in the United States are digital mammogram machines.
Another newer breast-imaging test called 3-D mammography (breast tomosynthesis) may provide an improved way of seeing through dense breast tissue. A 3-D mammogram combines multiple low-dose mammogram images to create a 3-D image of the breast. Though not available everywhere, 3-D mammography is becoming more common.
Additional screening tests are being developed for women with dense breasts, but unlike mammograms, none is proved to reduce the risk of dying of breast cancer.
Discuss your breast cancer screening options with your doctor. Together you may decide that, based on your risk factors, additional breast cancer screening tests may be right for you.
Feb. 25, 2015
- Wang AT, et al. Breast density and breast cancer risk: A practical review. Mayo Clinic Proceedings. 2014;89:548.
- Kerlikowske K, et al. Comparative effectiveness of digital versus film-screen mammography in community practice in the United States. Annals of Internal Medicine. 2011;155:493.
- Al Mousa DA, et al. What effect does mammographic breast density have on lesion detection in digital mammography? Clinical Radiology. 2014;69:333.
- AskMayoExpert. Breast cancer screening and options for supplemental screening in the dense breast. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2014.
- Pruthi S (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 9, 2015.