A study adds to evidence showing that an annual breast MRI or breast ultrasound along with an annual mammogram improves breast cancer detection in women with dense breasts.
Dense breasts have less fatty tissue and more non-fatty tissue compared to breasts that aren't dense. Doctors can tell if breasts are dense by the way they look on a mammogram.
Other research has shown that dense breasts:
- can be twice as likely to develop cancer as nondense breasts
- can be harder for mammograms to detect cancer in; breast cancers (which aren't fatty) are easier to see on a mammogram when they're surrounded by fatty tissue
So an aggressive breast cancer screening plan that includes two or more types of imaging tests makes sense for women with particularly dense breasts.
In this study, 2,309 U.S., Canadian, and Argentinean women with dense breasts and a higher-than-average risk of breast cancer had both a screening mammogram and a breast ultrasound each year. In the study's third year, all the women were offered breast MRI; 612 women had one. The researchers figured out how many cancers not found by mammogram were found by breast ultrasound or MRI.
Ultrasound and mammogram together found 82% of the breast cancers. Mammogram alone found only 53% of the cancers.
Ultrasound was very good at identifying cancer: 94% of the areas that doctors thought were cancer based on ultrasound results turned out to be cancer. Still, because there were many areas that doctors weren't sure about, only 10% of all the biopsies that were done turned out to be cancer. This means there were many false positives. A false positive is an area that looks like a cancer, but turns out to be normal.
Using all three screening methods each year -- ultrasound, mammogram, and MRI -- found 85% of the breast cancers. Adding breast MRI to the screening plan caused even more biopsies to be done and most of these biopsies turned out to be negative, which means there were more false positives.
For women with dense breasts, a breast cancer screening plan that includes both an annual mammogram and an annual ultrasound is better at finding breast cancer than having only an annual mammogram. Compared to MRI, ultrasound is less expensive. Adding an annual MRI to the plan also increases screening effectiveness, but at a much higher cost than ultrasound.
It's important to know that including a breast ultrasound or breast MRI in screening plans for women with dense breasts will cause more false positives. Besides the concern about a possible breast cancer diagnosis, a false positive usually means more tests (including biopsies) and follow-up doctor visits. The process can be very stressful and upsetting.
Based on the results of this and other studies, it's a good idea to ask your doctor if you have dense breasts, as well as about your risk of breast cancer. If your breasts are dense or your risk of breast cancer is above average, an aggressive screening plan that includes breast ultrasounds and/or breast MRIs along with mammograms may make sense for you. Ask your doctor to explain the risks and benefits of having ultrasound or MRI in your screening plan. Together you can develop a screening plan that's right for you.
Visit the Breastcancer.org Screening and Testing section to learn more about screening tests.