Supplemental Breast MRI to Women with Extremely Dense Breasts
A new Breast Cancer Surveillance Consortium (BCSC) study finds that targeting supplemental breast MRI to women with extremely dense breasts and elevated breast cancer risk enhances screening benefits while minimizing harms.
As of September 2024, a national rule requires all U.S. imaging centers to notify patients undergoing mammography of their breast density. This information has led many to wonder: "If I have dense breasts, is a mammogram enough?" A new BCSC study using computer simulations done with three Cancer Intervention and Surveillance Network (CISNET) modeling teams provides clarity on the population-level benefits of adding MRI to breast cancer screening with digital breast tomosynthesis (also known as “3D” mammography). While adding a breast MRI can find more cancers, it also increases the chance of "false positives"—results that look like cancer but turn out to be harmless after further testing or a biopsy. The study found that density shouldn't be the only factor in deciding to get an MRI. Instead, the combination of breast density and overall breast cancer risk needs to be considered. Here is how the research breaks down the harms and benefits:
- For Women with "Extremely Dense" Breasts and Higher-than-average Risk: Women in the highest breast density category ("extremely dense”) and with at least a two-fold higher-than-average risk (such as having a mother or sister who had breast cancer) would experience harms and benefits with 3D mammography screening plus supplemental MRI that are comparable to those experienced by average-risk women undergoing 3D mammography screening whether done every year or every other year.
- For Women at Average Risk: For women with dense breasts and no other major risk factors, adding an MRI to 3D mammography screening provides only a very small extra benefit compared to the significant increase in false positives and unnecessary biopsies.
- The Cost Factor: Right now, MRIs are expensive and are often not covered by insurance unless a women’s lifetime risk of breast cancer is high (above 20%). The study notes that supplemental MRIs would be more cost-effective for more women if the price of the MRI were lower and if "false positive" biopsy rates were also reduced.
Women receiving a notification that they have dense breasts, should consider speaking with their health professional and asking about their own overall risk of breast cancer and their breast density category. By considering both individual risk and breast density together, patients and their health professionals will be able to decide on an individualized screening plan.
Anna N.A. Tosteson, Natasha K. Stout, Yu-Ru Su, et al. Outcomes of Density-Targeted Supplemental Breast Magnetic Resonance Imaging Screening by Breast Cancer Risk: Long-Term Health and Economic Considerations. Ann Intern Med. [Epub 3 March 2026]. doi:10.7326/ANNALS-25-00792 [link]
The full article can be found here
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