What is breast density?
Breast density is a measure used to describe the proportion of the different tissues that make up a woman’s breasts. Breast density compares the area of breast and connective tissue seen on a mammogram to the area of fat. Breast and connective tissue are denser than fat and this difference shows up on a mammogram.
- High breast density means there is a greater amount of breast and connective tissue compared to fat.
- Low breast density means there is a greater amount of fat compared to breast and connective tissue.
Learn more about about the anatomy of the breast.
Breast density and breast cancer risk
Women with high breast density (as seen on a mammogram) are four to five times more likely to get breast cancer than women with low breast density [50-51].
How do health care providers use breast density?
At this time, health care providers do not routinely use a woman's breast density to assess her breast cancer risk. This is mainly due to the lack of a standard measure of breast density. While a measure of breast density may be recorded on a mammography report, this measure is not used to assess risk.
However, by looking at your mammogram or the measure of breast density, your provider may conclude that you have dense breasts and may suggest other types of breast screening.
Some states in the U.S. now have laws requiring that mammography reports include whether or not women have dense breasts. Although it seems like including this information should be helpful, currently there are no special recommendations or screening guidelines for women with dense breasts. In addition, although women with dense breasts appear to be at higher risk of breast cancer, it is not clear that lowering breast density will decrease risk. For example, getting older and gaining weight after menopause are both related to a decrease in breast density, but are also related to an increase in breast cancer risk.
If you have any concerns about your breast density, talk to your provider.
Learn more about breast density and mammography.
Screening for women with dense breasts
For women with high breast density, digital mammography may offer screening benefits over film mammography . Tumors in women with dense breasts can be easier to find with digital mammography than with film mammography. Most mammography centers now use digital mammography to screen all women.
Learn more about breast density and digital mammography.
Ultrasound and MRI
Ultrasound and MRI (in combination with mammography) are being studied to learn whether they improve detection in women with dense breasts compared to mammography alone.
Learn more about emerging areas in screening and early detection.
Learn more about screening for women at higher risk of breast cancer.