Study Finds DBT More Effective
Than Digital Mammography

Although digital breast tomosynthesis (DBT), also called 3D mammography, costs more than a digital mammography (DM) screening, it actually may help rein in cancer screening costs, according to preliminary findings presented by researchers from the Perelman School of Medicine at the University of Pennsylvania during the 2017 San Antonio Breast Cancer Symposium. The group analyzed 46,483 screening episodes—a single screening mammogram and all subsequent breast diagnosis-related costs for the following year—in two hospitals within the University of Pennsylvania Health System in 2012 and 2013.

"Early detection is critical to saving lives and lowering costs," said senior author Emily F. Conant, MD, chief of breast imaging at Penn Medicine. "Fortunately, breast imaging is more precise than ever thanks to DBT. Despite its higher initial cost, DBT is increasingly being embraced by radiologists nationwide. If you look at expenses associated with breast diagnosis in the following year after initial screening, DBT is more cost-effective in terms of health system or population level screening."

Previous studies modeling outcomes have demonstrated that DBT can be cost-effective. In this study, the authors analyzed actual costs and patient outcomes within a single health system where both DM and DBT screening occurred. They excluded any episodes in which the patient had a prior breast cancer diagnosis or reached 90 years of age before the end of the follow-up period. Fifty-three percent of women studied received DM, and 47% received DBT. 

The researchers tested DBT and DM according to four outcomes—true positive (TP), true negative (TN), false positive (FP), and false negative (FN) rates—by comparing the BI-RADS score, which was assigned at screening with data about subsequent cancer diagnosis. DBT was a more effective screening method. Compared to DM episodes, DBT episodes had lower FP (8.6% vs 10.8%) and higher TN (90.9% vs 88.7%, p<0.001) rates. There were no statistically significant differences between DBT and DM episodes with respect to TP and FN rates.

Although it screened more effectively, DBT did cost more than DM. Overall, average episode costs were higher for DBT compared to DM ($378.02 vs $286.62). This difference was driven by higher average screening costs ($215.94 vs $155.76), which approximated the additional charge for DBT, as well as follow-up costs ($23.67 vs $12.11). There was no significant difference in costs between DBT and DM episodes within the diagnosis or cancer treatment windows.

DM and DBT episodes had roughly the same average episode costs per woman screened for FP ($67.75 vs $65.71), FN ($4.63 vs $5.60), and TP ($85.80 vs $65.15) outcomes despite the higher cost per individual DBT study. The higher costs for TN ($219.84 vs $150.16) outcomes approximated the higher Centers for Medicare & Medicaid charge for DBT.

In addition to Conant, the coauthors on the study include Geraldine J. Liao, MD; Henry A. Glick, PhD; Marie B. Synnestvedt, PhD; and Mitchell D. Schnall, MD, PhD, all from Penn Medicine.

Funding for this study was provided by the National Institutes of Health (5U54CA163313-03). Conant is on the scientific advisory board of Hologic, Inc, and received a grant from Hologic, Inc. 

Source: Penn Medicine