Breast density care at the UVM Medical Center
Breast density refers to the ratio of fatty tissue to dense tissue in the breast, as seen on a mammogram. Dense breast tissue has more connective and glandular tissues, like milk glands, than fatty tissue. Having dense breasts is normal and common, occurring in up to 50% of women.
Having dense breast tissue may put you at a slightly increased risk of breast cancer. Additionally, dense breast tissue looks whiter than fatty breast tissue on mammography, as do many types of breast cancer. For that reason, the presence of dense breast tissue may make detecting breast cancer more challenging on a mammogram.
The University of Vermont Medical Center offers you the full range of diagnostic breast imaging services, from annual mammograms to advanced breast imaging exams that can provide more peace of mind for women with dense breasts. Our breast radiologists specialize in interpreting breast imaging exams, ensuring that you receive accurate results and, when necessary, recommendations for additional imaging — all provided by a knowledgeable expert.
We offer comprehensive breast imaging services to meet your needs, including:
- Experience that matters: At the UVM Medical Center, we use leading-edge digital equipment to perform the highest volume of exams in our service area. Studies have shown that the more mammograms a radiologist reads, the better they are able to interpret them, which ultimately leads to improved cancer detection and better care for patients.
- Outstanding clinical expertise: Our dedicated breast imaging physicians work closely with skilled mammography technologists, breast ultrasound sonographers, and breast MRI technologists, to produce the highest quality diagnostic images. These committed professionals strive to keep you as comfortable and relaxed as possible during your breast imaging exam or procedure.
- Latest 3D mammography: We offer state-of-the-art 3D mammography (tomosynthesis), an X-ray technology that takes multiple images of your breast tissue and offers greater detail than traditional 2D digital mammography. Improving cancer detection in all breast densities, this technology is especially beneficial for catching breast abnormalities in women with dense breast tissue.
- Supplemental screening for breast cancer: Women at high risk for breast cancer and/or who have dense breasts may require additional breast imaging tests to improve the chances of detecting breast cancer. The UVM Medical Center features leading-edge breast ultrasound and breast MRI services delivered by specialists specifically trained in these supplemental imaging techniques.
Diagnosing dense breasts
Breast density is the most common reason for a cancer not being seen on mammography. The fibrous connective and glandular tissue of dense breasts may make it more difficult for a radiologist to see subtle or unusual changes via standard mammography screening.
Dense breasts cannot be felt by you or determined through physical exam at your doctor’s office. Mammography provides the first information that you have dense breasts.
At the UVM Medical Center, our breast imaging radiologists may suggest additional breast imaging tests if your screening mammography reveals you have dense breasts.
Recommendations for supplementary screening
No strict medical guidelines exist for additional breast cancer screening for women with dense breasts. If you have dense breasts and/or other risk factors for breast cancer, such as family history, discuss your risk with your doctor. Having this discussion with your provider will help guide decisions about extra screening tests and determine the best imaging options for you.
We perform the full range of advanced breast imaging tests for the highest level of cancer detection. For the complete and thorough evaluation of women with dense breasts, our specially trained breast imaging team performs:
- 3D mammography (tomosynthesis)
- Breast ultrasound
- Breast MRI
Please be aware that some supplementary screenings for women with dense breasts or those at higher risk for breast cancer may not be covered by insurance. Talk with your doctor and check with your insurance company to help you make the best-informed decisions about breast cancer screening.
Breast Density Information for Health Care Providers
Breast density refers to the relative amounts of fatty versus glandular and fibrous breast tissue as seen on mammography. (One cannot assess density by physical exam). Although density is a continuous spectrum, radiologists divide breast density into 4 categories:
- Almost entirely fatty (10% of population)
- Scattered fibroglandular (40%)
- Heterogeneously dense (40%)
- Extremely dense (10%)
The last two are considered dense and the first two are considered non-dense. Density, on average, decreases with age with up to 70% of women in their 40's having dense breasts and 35-40% of women in their 70's having dense breasts.
Density is also affected by changes in body weight. Radiologists' assignment of density category is subjective and there is considerable inter-and intra-observer variability in the center of the spectrum (between scattered and heterogeneously dense) but much less variation at the two ends of the spectrum. So it is possible that some patients' density assessment category may change from year to year.
Masking Effect and Risk
While mammographic sensitivity is 98% in women with fatty breasts, the higher the density, the lower the sensitivity; with only 36-60% sensitivity in women with heterogeneously dense and extremely dense breasts. This is known as the “masking effect” of dense breast tissue. Besides being the number one cause of a missed cancer on mammography, breast density also imparts a higher risk for breast cancer. Those with heterogeneously dense breasts have 1.3-1.5 x the risk of those with scattered fibroglandular tissue and those with extremely dense breasts have 2.1-2.3 x the risk of the average woman.
Screening mammography has been proven to reduce the risk of death from breast cancer. All screening decisions need to balance the benefits of early detection and the potential harms of false positives and possible over-detection. This balance can only be achieved by considering patient values and preference.
Women with dense breasts may wish to supplement mammography with other testing in order to minimize the chance of a missed cancer on mammography and prevent diagnosis of cancer at an advanced stage. There are no current medical society guidelines or best practices in choosing who would benefit from supplementary screening in addition to mammography. There is growing consensus that those with extremely dense tissue would benefit from added testing. Each additional screening modality that is added to mammography has an increased risk of false positives and of over-diagnosis. Providers will need to be familiar with strengths and weaknesses of the available supplementary screening modalities.
You can see all the available supplementary technologies for breast cancer screening and their relative pros (increased cancer detection) and cons (false positives and radiation or contrast risks) at Dense Breast Info.
The following supplementary screening modalities are available at the University of Vermont Medical Center:
The first step in patient counseling is risk assessment. Risk assessment is important for all patients; dense or non-dense. Women with greater than 20% lifetime risk according to risk models that rely primarily on family history (for example Tyrer Cuzik, Claus or BRCAPRO) should have mammography supplemented with annual MRI. (American Cancer Society Guidelines for Breast Screening with MRI as an Adjunct to Mammography).
For women with average risk and non-dense breasts, annual mammography beginning at 40, 3D preferably, would be sufficient.Those with extremely dense breasts should consider supplementing mammography with ultrasound or MRI. Those with heterogeneously dense breasts might consider supplementary screening if they have other risk factors for breast cancer besides density or if there is a strong personal preference/drive for early detection.
There are several resources you can use to help guide discussions with patients about how to best screen and whether or not to supplement mammography with alternative screening methods.
At the UVM Medical Center, we generally perform 3D mammography for screening on most patients (except those that decline due to payment issues). As we use synthesized 2D in addition to 3D, there is no longer significantly increased radiation dose. 3D mammography has a lower false positive rate and higher cancer detection rate than 2D alone. A recent study showed this was true for all breast densities but adding 3D resulted in the most significant improvement for heterogeneously dense breasts with much less of an improvement in extremely dense breasts. (Breast Cancer Screening Using Tomosynthesis and Digital Mammography in Dense and Nondense Breasts).
Supplementary screening in addition to mammography will be covered by insurance to a variable degree. All supplementary screening is now covered in New York State by law and several other states are introducing legislation to that effect. In Vermont we have had increasing success in insurers covering 3D mammography but there are still some who do not. Coverage of supplementary ultrasound screening would be at the discretion of the insurer currently.
Resources For Dense Breasts
- Dense Breast Information
- Are you Dense
- Breast Cancer Screening & Dense Breasts - decision tool.
- The California Breast Density Information Group - flowcharts included.
- Dense Breasts: What Do Our Patients Need to Be Told and Why? Read full Text.
- CME Course Online
- American Cancer Society's guidelines for early detection of breast cancer.
- Summary of Expected Cancer Detection Rate chart
- Mammographic Breast Density: Effect on Imaging and Breast Cancer Risk - Renee W. Pinsky, MD; Mark A. Helvie, MD.
- Breast cancer screening in the era of density notification legislation: Summary of 2014 Massachusetts experience and suggestion of an evidence-based management algorithm by multi-disciplinary expert panel. Freer et al, Breast Cancer Res Treat. 2015 Sep;153(2):455-64. doi: 10.1007/s10549-015-3534-9. Epub 2015 Aug 20.
- Identifying Women With Dense Breasts at High Risk for Interval Cancer: A Cohort Study; Kerlikowske et al; Ann Intern Med. 2015;162(10):673-681. doi:10.7326/M14-1465
- Breast Density and Breast Cancer Risk: A Practical Review; Wang et al; Mayo Clinic Proceedings, 2014-04-01, Volume 89, Issue 4, Pages 548-557
- Mammographic Density and the Risk and Detection of Breast Cancer; Boyd et al, N Engl J Med 2007; 356:227-236, January 18, 2007,DOI: 10.1056/NEJMoa062790
- Mammographic Breast Density: Impact on Breast Cancer Risk and Implications for Screening, Phoebe E. Freer, RadioGraphics, 2015, 35, 2, 302, DOI.
- Opinion Piece: Viewpoint, The divide between breast density notification laws and evidence based guidelines for breast cancer screening: Legislating practice; Haas and Kaplan, JAMAintmed, July 2015
- Assessing Improvement in Detection of Breast Cancer with Three-dimensional Automated Breast US in Women with Dense Breast Tissue: The SomoInsight Study; Brem et al, Radiology, vol 274, issue 3, DOI.
- Benefits, harms, and cost-effectiveness of supplemental ultrasonography screening for women with dense breasts. Sprague BL, Stout NK, Schechter C et al (2014) Ann Int Med. doi.
- Current Status of Supplemental Screening in Dense Breasts, Commentary by Dr. Wendie Berg on the ASTOUND trial (reference below), Published online before print March 9, 2016, doi: 10.1200/JCO.2015.65.8674 JCO March 9, 2016 JCO658674.
- Adjunct screening with tomosynthesis or ultrasound in mammography-negative dense breasts (ASTOUND): Interim report of a prospective comparative trial. Tagliafico AS, Calabrese M, Mariscotti G, et al. J Clin Oncol, doi.
- Variation in Mammographic Breast Density Assessments Among Radiologists in Clinical Practice: A Multicenter Observational Study. Sprague et al; 2016 Ann. Intern. Med. Published online 19 July 2016
- Supplemental Screening for Breast Cancer in Women With Dense Breasts: A Systematic Review for the U.S. Preventive Services Task, Melnikow, et al, Ann. Intern. Med.2016;164(4):268-278. doi:10.7326/M15-1789.
- McDonald ES, Oustimov A, Weinstein SP, Synnestvedt MB, Schnall M, Conant EF. Effectiveness of Digital Breast Tomosynthesis Compared With Digital Mammography: Outcomes Analysis From 3 Years of Breast Cancer Screening. JAMA Oncol 2016. doi: 10.1001/jamaoncol.2015.5536