(HealthDay News) – A low malignancy rate is observed for Breast Imaging Reporting and Data System (BI-RADS) category 3 breast lesions detected by screening ultrasonography (US), according to research published in the December issue of Radiology.

Richard G. Barr, MD, PhD, of Radiology Consultants in Youngstown, Ohio, and colleagues analyzed data from the American College of Radiology Imaging Network 6666 protocol to prospectively validate predefined criteria for BI-RADS category 3 breast lesions detected at screening US.

The researchers found that 519 of 2,662 women (19.5%) had 745 BI-RADS category 3 breast lesions. Of the 745 category 3 lesions, 124 (16.6%) were biopsied, and six lesions (0.8%; 95% confidence interval, 0.3–1.7%) were malignant. Among the six malignant lesions, one was biopsied at six-month follow-up (N0), one at one-year follow-up (N0), and one at two-year follow-up (N1).

“Since BI-RADS category 3 lesions have a low malignancy rate (0.8%; 95% confidence interval, 0.3–1.7%) (six of 745 lesions) and since only one (0.1%) lesion had suspicious changes at short-interval follow-up and one (0.1%) lesion had suspicious changes at one-year follow-up, both of which showed signs of node-negative invasive ductal carcinoma, a recommendation of yearly follow-up for BI-RADS category 3 lesions may be appropriate,” the authors write.

Several authors disclosed financial ties to biomedical companies, including makers of ultrasound equipment.

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