Study Highlights MRI Screening of cancer in Dense Breasts: Benefits with Trade-Off of False Positives
USA: Researchers have found in a new study that among high-risk patients with extremely dense breasts, adding biennial MRI to routine screening may modestly reduce breast cancer mortality compared to tomosynthesis alone. However, this approach is associated with increased false-positive rates, highlighting a balance between improved detection and potential overdiagnosis.
The findings, published in Annals of Internal Medicine, are based on a comprehensive simulation study led by Anna N.A. Tosteson and colleagues from Dartmouth. The research evaluated the long-term clinical and economic impact of incorporating supplemental breast magnetic resonance imaging (MRI) into standard screening strategies, particularly in women with dense breast tissue.
Breast density affects cancer detection, as dense tissue can mask tumors on imaging. With mandated density notifications, there is an increasing focus on optimizing screening strategies across different breast cancer risk groups. To explore this, researchers modeled outcomes in women aged 40 years and above, from average risk to those with up to fourfold higher risk.
The study compared digital breast tomosynthesis (DBT) alone and with supplemental MRI for women with extremely dense breasts. It evaluated different starting ages (40, 45, 50 years) and screening intervals (annual or biennial), assessing lifetime outcomes from a U.S. healthcare payer perspective.
The following findings were reported:
- Digital breast tomosynthesis alone reduced breast cancer mortality, preventing 7.4–10.5 deaths per 1,000 average-risk women and up to 33.6 deaths per 1,000 in high-risk women.
- Adding MRI for women with extremely dense breasts resulted in a small additional reduction in mortality, with 0.1–0.8 fewer deaths per 1,000 women screened.
- The addition of MRI significantly increased harms, particularly false-positive biopsy recommendations.
- Supplemental MRI led to 22–186 additional false-positive biopsies depending on risk level and screening strategy.
- In some higher-risk groups, the ratio of false positives to deaths prevented was similar to that observed with DBT alone in average-risk women.
- Biennial DBT combined with MRI starting at age 50 was more effective in reducing deaths compared to DBT alone starting at age 45.
- However, this combined approach was less cost-efficient than DBT alone.
- Cost-effectiveness was influenced by MRI costs, baseline cancer risk, and rates of false-positive findings.
The authors note that supplemental MRI screening may be a reasonable consideration for women with extremely dense breasts who also have at least double the average risk of breast cancer. In such cases, the balance between benefits and harms appears similar to existing screening approaches, particularly if efforts are made to reduce MRI costs and improve diagnostic accuracy.
Overall, the study highlights the importance of personalized screening strategies, taking into account both breast density and individual risk profiles. While supplemental MRI offers additional detection benefits, its broader implementation will depend on addressing concerns related to cost and potential overdiagnosis.
Reference:
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
Next Story