Adding MRI to 3D Mammograms May Save Lives of Women With Extremely Dense Breasts

Dense breasts make it harder to spot cancer on routine mammograms. Computer models suggest that if women with extremely dense breasts receive both 3D mammograms and MRI screening every two years, fewer would die from breast cancer. But there was a catch: The models found more women had to go back for more testing that ultimately revealed they didn’t have cancer (called false- positive results).  The study was published in JAMA Internal Medicine.

A false-positive result is when a screening test shows an abnormal area that looks like cancer but turns out to be normal. Ultimately the news is good: no breast cancer. But the suspicious area usually requires follow-up with more than one doctor, extra tests, and extra procedures, including a possible biopsy. Research suggests that some women who get a false-positive result are less likely to get the recommended follow-up tests.

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  3D mammogram screening every two years starting at age 50 for all women prevented 7.4 deaths from breast cancer per 1,000 women; starting 3D mammograms at age 40 prevented 8.5 breast cancer deaths per 1,000 women.

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  There were 884 false-positive results per 1,000 women when screening started at age 50 and 1,392 when starting at age 40.

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  Adding MRI to 3D mammograms every two years starting at age 40 for women with dense breasts prevented 9.4 deaths per 1,000 women, but also returned 1,850 false-positive results.

If you have extremely dense breasts, starting breast cancer screening early and receiving MRIs and 3D mammograms may reduce your risk of death from breast cancer. But these additional screenings may also lead to more false-positive follow-up tests, including biopsies of suspicious areas that aren’t cancer. 

The U.S. Food and Drug Administration (FDA) now requires all mammography reports to include an assessment of breast density. If you have dense breasts or a higher-than-average risk of breast cancer for another reason, such as a genetic mutation, talk to your doctor about a screening plan that’s tailored to your level of risk and gives you peace of mind. 

Because of the new FDA dense breast reporting requirement, the researchers noted that healthcare professionals and policymakers need information on the benefits and harms of different types of screening for different breast densities. 

The researchers ran three breast cancer simulation computer models that used data from the U.S. Breast Cancer Surveillance Consortium, a network of breast imaging information. The models made projections of lives saved and false-positive results using 60 different breast cancer screening strategies on an average woman born in 1980 with average breast cancer risk.

The study found that any type of screening was better than no screening and that screening every year saved more lives, but also returned more false-positive results.

Starting at age 50 prevented 7.4 breast cancer deaths and returned 884 false-positive results per 1,000 women; starting at age 40 prevented 8.5 deaths and returned 1,392 false-positives.

Starting at age 50 prevented 9 breast cancer deaths and returned 1,307 false-positive results per 1,000 women; starting at age 40 prevented 10.5 deaths and returned 2,139 false-positives.

Dense breasts are BI-RADS categories C and D. Starting at age 50 prevented 8 deaths and returned 1,089 false-positive results per 1,000 women; starting at age 40 prevented 9.4 deaths and returned 1,850 false-positives.

Starting at age 50 prevented 9.6 breast cancer deaths and returned 1,792 false-positive results per 1,000 women; starting at age 40 prevented 11.4 deaths and returned 3,200 false-positives.

Extremely dense breasts are BI-RADS category D. Starting at age 50 prevented 7.5 breast cancer deaths and returned 919 false-positive results per 1,000 women; starting at age 40 prevented 7.6 deaths and returned 1,519 false-positives.

Starting at age 50 prevented 9.1 deaths and returned 1,383 false-positive results per 1,000 women; starting at age 40 prevented 10.7 deaths and returned 2,415 false-positives.

Stout NK, et al. Breast Cancer Screening Using Mammography, Digital Breast Tomosynthesis, and Magnetic Resonance Imaging by Breast Density. JAMA Intern Med. Published online August 26, 2024.