Medically Reviewed by W. Shawn Conwell, MD, FACR

Mammograms are the standard diagnostic tool for spotting breast cancer. On the mammogram, normal breast tissue appears as black while most forms of breast cancer show up as white.

“On the mammogram of normal breasts, the white cancer shows up against the black normal tissue like a star in the night sky,” says McLeod Radiologist W. Shawn Conwell, MD. “However, if a woman’s breasts are dense, the mammogram image has lots of white (tissue) and no black (fat). Finding a cancer in this circumstance is like searching for a polar bear in a snowstorm. It’s extremely difficult to see a cancer in dense breasts. In fact, about 50 percent of cancers in extremely dense breasts are completely invisible on a mammogram.”

Radiologists classify breast tissue into four categories:

1. Breasts are almost entirely fatty
2. Breasts with scattered areas of fibro-glandular densities
3. Breasts with dense and normal tissue mixed throughout (heterogeneous), which may obscure small masses
4. Breasts that are extremely dense, which lowers the sensitivity of mammography

Density is not related to breast size, shape or texture. Younger women tend to have denser breasts, but many older women also have this composition. You must get a mammogram to know if you have dense breasts. Approximately 40 percent of the screening age population (women age 40 and older) have dense breast tissue (categories c and d).

BEYOND THE MAMMOGRAM
However, radiologists have long been aware that mammography is not optimally suited for imaging dense breasts. Recent research established the ability of breast ultrasound to increase cancer detection rates by nearly 60 percent, when used as a supplement to screening mammography in women with dense breasts.

In addition to breast ultrasound, the use of breast tomography (3D mammography) has also been shown to increase cancer detection rates in all women, including those with dense breasts. The use of breast tomography also reduces unnecessary call back examinations, cutting the false positive rate of screening mammograms nearly in half.

ACTION YOU CAN TAKE
In the following resources, you’ll find accurate, scientific and consensus-based information on breast tissue density.

• A consensus statement recognized by the American College of Radiology and collaboratively produced with the Society of Breast Imaging can be found at www.mammographysaveslives.org by clicking on “Tools and Resources.” This downloadable brochure is available in both English and Spanish.
• More comprehensive information can be found at www.densebreast-info.org.

If you have any further questions about these services, please feel free to call the McLeod Breast Imaging Center at 843-777-6317.

Have a question?  Ask a Cancer Specialist.

To schedule your 3D mammogram at McLeod Health in Florence, Cheraw, Clarendon, Dillon, Loris or North Myrtle Beach, call (843) 777-2095 or click here.