Detecting and characterizing breast cancer is a constant challenge, especially in women with dense breast tissue. About 43% of women 40 to 72 have dense breasts, which means they have a higher proportion of fibroglandular tissue compared to fatty tissue. The dense tissue can hide signs of breast cancer, making diagnosis more difficult. In fact, standard, two-dimensional mammography may miss more than a third of cancers in dense breasts.1
Yet having dense breasts doubles your personal risk of breast cancer.2 That’s why it’s so important to know if you have dense breasts.
Unfortunately, most women have no idea. In one study, just 58 percent of women had even heard of breast density, and just half of those knew it affected breast cancer detection. In addition, just 53 percent knew it was a risk factor for breast cancer.3
The issue is so important that many states have passed laws requiring that mammography centers inform women if they have dense breasts. And, in early 2019, the US Food and Drug Administration proposed the first major policy change to mammography services in more than 20 years to require that all mammography providers in the US tell women if they have dense breasts.
One reason it’s so important to know if you have dense breasts is because you may need a different type of breast cancer screening. They include:
Digital breast tomosynthesis, or 3-D mammography. This type of screening is more accurate than the traditional 2-D mammogram. Combined with 2-D mammography, it significantly improves cancer detection in all women, as well as those with dense breasts.4 Some studies also suggest that even 3-D alone improves breast cancer detection.5 Most mammography centers offer 3-D mammography, although your health insurance may not cover it.
Handheld ultrasound and automated breast ultrasound (ABUS). Ultrasound uses high-frequency sound waves instead of radiation to create images of the breast. It is often used to investigate a suspicious finding from a mammogram and as a supplemental exam for women with dense breast tissue. Adding it to mammography can improve breast cancer detection by nearly 40 percent over mammography alone.6 The ABUS type of ultrasound provides 3-D images of the breast tissue, which offers a better view, and takes less time than traditional ultrasounds.
Contrast-enhanced spectral mammography (CESM). Contrast-enhanced spectral mammography highlights unusual blood flow in the breast, which can signify a tumor. Radiologists often use CESM instead of MRI in women with dense breasts who had an inconclusive mammogram and ultrasound. It can be particularly beneficial for women who can’t undergo MRI because of cost, wait time, contraindications such as metal implants or claustrophobia, or other issues.
MRI. An MRI uses powerful magnets to detect abnormalities in breast tissue. While it is an excellent option for women at high risk of breast cancer and those whose mammogram and ultrasound were inconclusive, it is also expensive, may entail waiting times, and can be challenging for women who are claustrophobic.4
Breast-computed tomography (CT). This type of scan uses radiation to produce a 3-D image of the breast, but the images are even more detailed than those provided by 3-D mammography. Like other more advanced options, it is used after a mammogram to provide a more definitive diagnosis, particularly in women with dense breasts.
You may find that your breast density decreases after menopause, although hormone replacement therapy can increase it. Losing weight can also reduce breast density, as can certain changes in your diet.7
And to answer your question about how to know if you have dense breasts? Ask the radiologist who read your last mammogram.
- Boyd NF, Guo H, Martin LJ, et al. Mammographic density and the risk and detection of breast cancer. N Engl J Med. 2007;356(3):227-236.
- Nelson HD, Zakher B, Cantor A, et al. Risk factors for breast cancer for women aged 40 to 49 years: a systematic review and meta-analysis. Ann Intern Med. 2012;156(9):635-648.
- Rhodes DJ, Radecki Breitkopf C, Ziegenfuss JY, Jenkins SM, Vachon CM. Awareness of breast density and its impact on breast cancer detection and risk. J Clin Oncol. 2015;33(10):1143-1150.
- Lee CI, Chen LE, Elmore JG. Risk-based Breast Cancer Screening: Implications of Breast Density. Med Clin North Am. 2017;101(4):725-741.
- Zackrisson S, Lang K, Rosso A, et al. One-view breast tomosynthesis versus two-view mammography in the Malmo Breast Tomosynthesis Screening Trial (MBTST): a prospective, population-based, diagnostic accuracy study. Lancet Oncol. 2018;19(11):1493-1503.
- Brem RF, Lenihan MJ, Lieberman J, Torrente J. Screening breast ultrasound: past, present, and future. AJR Am J Roentgenol. 2015;204(2):234-240.
- Vachon CM, Kushi LH, Cerhan JR, Kuni CC, Sellers TA. Association of diet and mammographic breast density in the Minnesota breast cancer family cohort. Cancer Epidemiol Biomarkers Prev. 2000;9(2):151-160.