Breast density is a common topic when it comes to screening mammography. If you have questions about breast density, you are not alone, and the next few paragraphs may have some of the answers.
What is Breast Density?
All breasts contain glands and fat. The amount of glands a breast has compared with the amount of fat is called breast density. A breast with more glands and little fat is considered a dense breast, and a breast with fewer glands and more fat is considered a fatty breast. Dense breasts are very common and normal. About 40% of women over age 40 have dense breasts. Dense breasts are more common before menopause, and breast density generally decreases with age.
Why Does Breast Density Matter?
Each time you have a mammogram, your radiologist checks your breast density for two reasons. First, dense breasts have a higher chance of developing breast cancer. Second, it is more difficult to find breast cancers in dense breasts compared with fatty breasts. This is known as masking. For these reasons, some states now require that radiologists include your breast density with your mammography results.
Are there other options for breast cancer screening?
Screening mammography has been shown to decrease the chance of dying from breast cancer. Because dense breasts can hide cancers, women with dense breasts may also benefit from additional screening. The additional screening tests described below, when combined with standard mammography, may help find breast cancer when it is smaller.
Standard mammograms are two-dimensional pictures. A newer technology called digital breast tomosynthesis (DBT) is sometimes referred to as 3D mammography. 3D mammography allows radiologists to see in between layers of overlapping breast tissue. This helps radiologists find some breast cancers that can’t be seen on standard mammography.
3D mammography has another potential benefit. Sometimes after a mammogram, patients are asked to come back for more pictures to make sure something seen by the radiologist is not breast cancer. With 3D mammography, fewer patients are called back for more pictures after a screening mammogram.
The amount of radiation from a 3D mammogram is about the same as a standard mammogram. If you have standard and 3D mammography combined, then the radiation is about double that of standard mammography alone, but still within safe limits. New software can reduce the dose by half.
Another option for breast cancer screening in dense breasts is adding screening ultrasound to standard mammography. Researchers have drawn three main conclusions about the combination of screening ultrasound and mammography in dense breasts: 1) the combination finds more breast cancers than mammography alone, 2) the combination results in a higher likelihood of a patient being called back for more pictures compared with screening mammography alone, and 3) the combination results in more biopsies for findings that turn out not to be cancer. While adding screening ultrasound to screening mammography finds more cancers, it finds more things that are not cancer too.
Ultrasound does not use radiation, so there is no added radiation from adding screening ultrasound to mammography.
Magnetic Resonance Imaging (MRI)
Some women are at very high risk of getting breast cancer, like women who have the breast cancer gene, or women who had radiation for lymphoma. Adding screening MRI to screening mammography is recommended for all patients at very high risk for breast cancer, regardless of breast density, because MRI is the best test at finding breast cancer. If a high-risk patient has screening MRI, then screening ultrasound is not needed. Researchers are working on making breast MRI faster and cheaper, while still finding any breast cancer that may be present. MRI isn’t perfect, though. It also can show abnormalities that require additional testing or biopsy, that turn out not to be cancer.
Similar to ultrasound, MRI does not involve radiation.
Dense breasts are common and normal. Because women with dense breasts are at a higher risk of breast cancer and because dense breasts make cancer harder to find, additional screening tests may be useful for patients with dense breasts. These tests include 3D mammography, screening ultrasound, and MRI. If you have questions about breast density or which screening test is right for you, remember that your doctor is here to help.
You can also get more information on this website: densebreast-info.org