Supplemental screening ultrasonography would add substantial costs while providing little clinical benefit after a negative screening mammography in women with dense breasts, according to three validated microsimulation models.
Adding ultrasound screening after a negative mammogram for women with heterogeneously or extremely dense breasts would cost more than $100,000 per quality-adjusted life-years (QALY) gained, compared with mammography screening alone, the models consistently showed.
Using simulated cohorts of women aged 50-74 years who were undergoing biennial mammography screening, the three models yielded similar results with respect to the estimated benefits and harms of three screening strategies: mammography alone, mammography plus screening ultrasonography after a negative mammography result in women with extremely dense breasts, and mammography plus handheld screening ultrasonography after a negative mammography result in women with heterogeneously or extremely dense breasts.
Brian L. Sprague, Ph.D., of the University of Vermont, Burlington, and his colleagues reported the findings in the Dec. 9 edition of Annals of Internal Medicine .
The findings could help influence the current national debate over breast density notification laws. At least 19 states have already enacted legislation that requires that women with dense breasts be informed about their breast density and about the availability of supplemental screening tests such as ultrasound. The high rate of false-negative mammograms in women with dense breasts is driving patient advocates to seek similar laws across the country. There’s even a bill under consideration at the national level.
The researchers found that mammography screening alone, across the models, reduced breast cancer deaths from 25.4 per 1,000 women in the absence of screening, to 19.7 per 1,000 women. There was an increase in total costs of approximately $1 million per 1,000 women.
Compared with biennial mammography screening alone, supplemental screening ultrasonography for women with extremely dense breasts would avert 0.30 additional breast cancer deaths and produce 1.1 additional QALY per 1,000 women, or about 9.6 hours per woman. These gains would come at a cost of 189 biopsies resulting from false-positive findings and $287,000 per 1,000 women with extremely dense breasts (a cost-effectiveness ratio of $246,000 per QALY gained).
In women with heterogeneously or extremely dense breasts, supplemental ultrasonography would avert 0.36 additional breast cancer deaths and produce 1.7 additional QALYs per 1,000 women. But these benefits would come at a cost of 354 biopsies resulting from a false-positive finding, and $560,000 per 1,000 women with heterogeneously or extremely dense breasts (a cost effectiveness ratio of $325,000/QALY gained), according to the study.
Restricting supplemental screening ultrasonography only to those with extremely dense breasts improved efficiency somewhat, but even this approach was not cost-effective by most standards.
The study used established, validated Cancer Intervention and Surveillance Modeling Network microsimulation breast cancer models, which incorporate evidence from clinical trials and observational studies.
“The models simulated life histories of women who were at risk for breast cancer, had screening, were treated for breast cancer diagnosed by screening or clinical detection, and were at risk for dying of breast cancer and other causes,” the researchers wrote, adding that the models differed in structure, but used common inputs.
The researchers called for further studies evaluating the potential role of other imaging methods, such as magnetic resonance imaging and digital breast tomosynthesis, in screening for women with dense breasts.
This study was funded by the National Cancer Institute. Dr. Sprague and several of the study authors reported receiving grant funds from the National Cancer Institute during the conduct of the study.
