By Dr. Nila H. Alsheik
Digital breast tomosynthesis (DBT), or 3D screening mammography, has again been solidified as the gold standard of care for breast screening according to a recent study published in Academic Radiology, and more and more facilities are offering this technology.
Despite this trend, however, utilization rates at many facilities nationwide still remain suboptimal, with only partial conversion rates to DBT. For facilities aiming for the highest patient outcomes, including reduced recall rates and optimized cancer detection rates, conversion rates over 75 percent to DBT screening confer the highest benefits.
Standardization of clinical protocols in the screening and diagnostic setting is critically important in the era of DBT. DBT confers lower recall rates and higher cancer detection rates, regardless of breast density. The data, therefore, supports uniform screening DBT utilization in all patients, and not just in those who have heterogeneously or extremely dense breast tissue. Conversely, patient care and facility performance are not optimized in hybrid screening environments where there is more than 25 percent 2D screening utilization.
To compare outcomes associated with breast cancer screening with 2D mammography alone versus in combination with DBT, researchers analyzed patient-level demographics, calculated risk levels, and clinical outcomes of more than 190,000 DBT exams and more than 130,000 DM/2D screening examinations over a two-year period at 39 imaging facilities across two healthcare systems. The study, which utilized multiple benchmarks including cancer and invasive cancer detection rates, specificity, tumor grade, size and stage of tumor at diagnosis and nodal status, demonstrated that DBT conferred a 22 percent higher cancer detection rate, as well as a sustained decrease in recall rates across the entire cohort, compared to 2D alone.
The implications of the study are far-reaching, as recalls due to false positives have been shown to create anxiety and reduce patient compliance with future screening mammography. As such, heightened sensitivity and specificity in mammography not only affects the rate of cancer detection, but potentially reduces morbidity and cost arising from unnecessary downstream procedures and imaging. In addition to being more effective than 2D alone, DBT recall rates were also lower at sites that predominantly performed DBT screening (8.02 percent), compared to facilities that perform a mix of 2D alone and DBT screening (10.43 percent).
Among women recalled for further testing, those screened with DBT had a more streamlined diagnostic workflow, as 15.1 percent of recalls after DBT did not include diagnostic mammography, compared to only 3.9 percent for 2D alone. In addition, those recalled after DBT experienced a faster time to biopsy, with the average being 19 days with DBT, compared to 23 days with 2D; and faster time to diagnosis as well, averaging 10 days with DBT, compared to 13 days with 2D. While these findings persisted in all age groups, races and breast densities across both health systems, they were more pronounced in facilities performing predominantly DBT screening, demonstrating DBT not only offers a more efficient screening option, but that increasing its utilization is associated with improved resource utilization profile.
DBT also helped physicians find smaller, earlier-stage cancers, which are easier to treat and would have been missed on 2D mammograms. Despite DBT’s superiority compared to 2D alone, the USPSTF still maintains an insufficient rating in the 2015 USPSTF Breast Cancer Screening guidelines, due in part to a lack of studies with sufficient follow-up information needed to calculate sensitivity and specificity. To address this, the study analyzed the largest number of DBT exams ever in a single study, and found DBT increased both sensitivity and specificity when compared to 2D alone, thus filling this gap in evidence.
Facilities looking to both exceed performance benchmarks and deliver exceptional patient care should look toward adopting and fully implementing screening DBT. Facilities that predominantly perform DBT experience lower recall rates, and among those recalled, experience decreased utilization of diagnostic mammography, faster time to biopsy, and faster time to final diagnostic resolution. With all of these proven clinical benefits in mind, facilities with low utilization should prioritize increasing these rates in order to maximize the full benefits of DBT usage for both the practice, and the patient.
About the Author: Dr. Nila H. Alsheik is a diagnostic radiologist at Advocate Lutheran General Hospital in Park Ridge, Illinois.