DBT is a relatively new screening practice and was only approved by the Food and Drug Administration in 2017. It uses an x-ray tube that glides in an arc-shape and uses low levels of radiation to image the breast from various angles. Up until now, research only showed us how effective the screening is in the first round of testing before detection rates are expected to escalate. Those early studies showed that DBT had higher detection rates than DM, and more patients were called back after showing suspicious areas in their scans.
Lead study author and professor and chief of breast imaging at the Perelman School of Medicine at the University of Pennsylvania, Emily F. Conant, MD, ventured out to determine the accuracy and long-term outcomes of using DBT. They looked at over 56,000 DBT scans and 10,500 previous DM scans over a five-year period, and her team compared the findings to results from local cancer registries.
Ultimately, the researchers found that DBT detected more cancer than DM, with 6 cases identified for every 1,000 DBT scans compared to 5.1 per 1,000 DM images. Recall rates for DBT was 8 percent whereas DM was 10.4 percent. Nearly a third of cancers detected by DBT had a weaker prognosis, and that figure was 25 percent for DM scans. These numbers remained constant over the five years of tomosynthesis imaging.
Dr. Conant attributes DBT’s high efficacy rates to the fact that it allows for more precise visualization. The breast is presented in multiple layers, preventing any overlapping or obscuring of breast tissue.
"With tomosynthesis you can remove some of the overlapping or obscuring breast tissue so that both normal and abnormal findings are better seen," said Dr. Conant. "That provides both improved cancer detection and decreased false positives."