Two are better than one: Adding tomosynthesis decreases recall rates

Patients undergoing conventional mammography paired with tomosynthesis had significantly lower screening recall rates than those receiving mammography alone, according to a study published in the December issue of Radiology.

The impact on recall rates was particularly strong for those younger than 50 and those with dense breasts, reflecting tomosynthesis’ ability to reduce false-positives in that patient population.

“Recent work has evaluated the performance of tomosynthesis in a variety of observer performance studies, which collectively have established that the combination of digital breast tomosynthesis with conventional digital mammography can decrease screening mammography recall rates without having a negative effect on sensitivity in the detection of malignancy,” wrote Brian M. Haas, MD, of Yale University School of Medicine in New Haven, Conn., and colleagues.

Haas and colleagues created a study to evaluate the performance of breast tomosynthesis in clinical practice by identifying which patients experienced the greatest reduction in screening mammography recall rates and to assess the cancer detection rate.

Participants were selected from patients presenting for screening mammography in a one year period between October 2011 and September 2012 at four clinical sites. These sites all used digital mammography and included breast imaging clinics in an academic tertiary care hospital, two outpatient radiology centers, and a mobile van-based mammography unit. Tomosynthesis was the preferred method of screening when available, and was performed in combination with mammography when feasible.

Eight breast imaging radiologists interpreted the exams. Recall rates were calculated for the two groups and stratified by breast density and age. During the study, 13,158 patients underwent screening mammography, 6,100 underwent tomosynthesis plus mammography, and 7,058 underwent digital mammography alone.

The overall recall rates for patients in the tomosynthesis group were 8.4 percent and 12 percent for the conventional imaging group. When the recall rates were stratified according to breast density, results demonstrated reduced recall rates for the combination compared with mammography alone for all breast density groups. Significant differences were found for scattered fibroglandular breast density, heterogeneously dense breasts, and extremely dense breasts.

When stratified according to patient age, reduced recall rates were evident with tomosynthesis plus mammography for all age groups. Significant differences were found in patients younger than 40, patients 40 to 40 years old, and patients 60 to 69 years old.

Both younger age and greater breast density were significantly associated with higher risk of recall.

There was a 9.5 percent increase in the cancer detection rate with tomosynthesis; 2,018 women would need to be screened with tomosynthesis to detect one additional cancer beyond that detected by mammography individually. 

“When adopted, tomosynthesis promises to alter the mammography workflow by decreasing screening rates and to subsequently improve the mammography experience for many women,” wrote Haas and colleagues.