DBT, availability of prior mammograms lead to fewer false-positive recalls

Digital breast tomosynthesis (DBT) leads to fewer false-positive (FP) recalls than full-field digital mammography (FFDM), according to new findings published in Academic Radiology. The patient’s age and the availability of prior mammograms were also important factors.

“Our hypothesis was that the accuracy of screening mammography is impacted by a set of variables,” wrote co-author Evan L. Honig, BS, Johns Hopkins University School of Medicine in Baltimore, and colleagues. “Once better defined and understood, these variables may be leveraged to improve screening outcomes.”

The researchers reviewed data from more than 22,000 breast cancer screening mammograms performed from August 31, 2015, to Sept. 30, 2016, at a single institution. FP recalls were defined as findings given a BI-RADS category 1 or 2 assessment with a full year of cancer-free follow-up, exams given a BI-RADS category 3 assessment with two years of cancer-free follow-up or a breast biopsy with benign pathology.

Overall, the data revealed a recall rate of 8.6 percent. The recall rate was 8 percent for DBT and 10.6 percent for FFDM. While 91.6 percent of those recalls were FP, 93 percent of the FFDM recalls were FP and 91 percent of the DBT recalls were FP.

There were also fewer FP recalls when prior mammograms were available and when there had been a previous benign breast biopsy. In addition, the mean age for the FP group (56.1 years old) was significantly lower than the mean age for the true positive group (62.9 years old).

Noting that their finding related to prior mammograms being available has been echoed by other studies, the authors emphasized the importance of radiologists being given relevant images whenever possible.

“Given these findings, imaging centers should prioritize retrieval of relevant prior images from outside facilities and engage patient participation in obtaining their own prior mammograms,” the authors wrote. “Ideally, images should be interpreted when comparisons are available, which can be a challenge within a reasonable time frame. In the future, one can envision a greater sharing of images, perhaps via a cloud storage solution. Women should be educated to be more proactive in obtaining prior exams given the importance.”

Honig et al. also noted that some of the variables they explored did not appear to make a significant difference when it came to FP recalls.

“We did not see any impact on false positive recall results with prior history of high-risk breast lesions, family history of breast or ovarian cancer, hormone use, race, or BMI,” the authors wrote. “This is in contrast to some previous literature suggesting false positive rates were higher for women who have a first degree relative with breast cancer and low (<30 kg/m2) BMI. These differences could be related to the small numbers of patients that were in some of these groups.”