Short-interval follow-up not needed for MB circumscribed masses on screening US

Multiple bilateral (MB) circumscribed masses seen at screening ultrasound (US) are generally benign, with no malignancies observed in a recent study of more than 2,000 patients with an elevated risk for breast cancer, according to results published in the September issue of Radiology.

Lesions of this type are suitable for diagnostic follow-up in one year, followed by continuation of screening if they remain stable, according to Wendie A. Berg, MD, PhD, of the University of Pittsburgh School of Medicine and American College of Radiology Imaging Network, Philadelphia, and colleagues.

At screening mammography, MB circumscribed masses have been reported in 1.7 percent of studies and are classified as Breast Imaging Reporting and Data System (BI-RADS) category 2, meaning the mass is benign. At screening whole-breast US, such masses can include complicated cysts, clustered microcysts and solid masses, according to the authors.

To determine the malignancy rate of MB circumscribed masses detected at screening US, Berg and colleagues conducted a prospective trial of women with an elevated risk for breast cancer who were screened at 21 international sites. Cancer detection rates were evaluated for three rounds of annual supplemental screening US. A total of 6,103 screening studies representing 2,172 participants were evaluable and included in the study.

Results showed 1,454 patients had unique findings at US, with 135 (6.2 percent of the overall cohort) having unique MB circumscribed masses. In the 127 MB circumscribed benign-appearing masses with at least two years of follow-up, there were no malignancies. Berg and colleagues noted, however, that based on the study’s sample size, the true malignancy rate for such lesions could be as high as 2.9 percent.

Factoring in this low malignancy rate, short-interval follow-up and biopsy could probably be eschewed in favor of diagnostic follow-up at one year. “Follow-up adds cost and can be time consuming if each such mass requires documentation and measurement, particularly with hand-held whole-breast US,” wrote Berg and colleagues.

The authors underscored the importance of scrutinizing the features of each mass, as 82 of the 135 women with MB circumscribed masses also had a solitary lesion at US. The malignancy rate among these masses in patients with at least two years of follow-up was 0.4 percent.

“We recommend diagnostic follow-up at one year for multiple bilateral circumscribed benign-appearing masses identified at screening US, with resumption of screening thereafter if the mass is stable, but we recognize that larger studies need to be performed to document that this is a valid approach,” wrote the authors.

The study comes on the heels of other research, conducted by Richard G. Barr, MD, PhD, of Northeast Ohio Medical University in Youngstown, and colleagues, which found US-detected lesions assessed as BI-RADS category 3 had a malignancy rate of 0.8 percent, suggesting an extension of the follow-up interval from six months to one year might be appropriate.