Application of the downgrade criteria to supplemental screening ultrasound for women with negative mammography but dense breasts

We investigated whether the application of the downgrade criteria to supplemental screening ultrasound (US) for women with negative mammography but dense breasts can reduce the rate of Breast Imaging Reporting and Data System (BI-RADS) categories 3 to 4a without a loss of cancer detection. This retrospective study was approved by the Institutional Review Board, and the need to obtain informed consent was waived. A total of 3171 consecutive women (978 women, 1173 women, and 1020 women in the first, second, and third year, respectively) with negative mammography but dense breast who underwent radiologist-performed, hand-held supplemental screening US from March 2010 to February 2013 were included. Downgrade criteria for BI-RADS category 2 were complicated cysts ≤5 mm observed as circumscribed, homogeneous, and hypoechoic lesions and circumscribed oval-shaped solid masses ≤5 mm. Changes in the distribution of BI-RADS category, biopsy rate, and cancer detection yield over 3 years were analyzed. Performances of less-experienced (12 fellows with <2 years of experience) and experienced (3 staffs with >12 years of experience) radiologists were compared. Outcomes of initial examinations (prevalence screening) and noninitial examinations (incidence screening) were compared. Application of the downgrade criteria reduced BI-RADS categories 3 to 4a in both less-experienced (from 39.4% to 16.0%, P < 0.001) and experienced radiologists (from 22.6% to 11.1%, P < 0.001) over 3 years. Biopsy rates also significantly decreased from 6.5% to 2.4% (P < 0.001). Cancer detection yield of supplemental screening US was 2.8 per 1000 examinations (9 of 3171: 2 ductal carcinoma in situ and 7 invasive cancers). There were no differences in cancer detection yield per each year (P = 0.539). There was no interval cancer. In noninitial examinations, BI-RADS categories 3 to 4a rates, biopsy rates, and cancer detection rates were lower compared to initial examinations. Application of the downgrade criteria reduced BI-RADS categories 3 to 4a without a loss of cancer detection. We suggest that our downgrade criteria can be used to reduce the false positive rate in the supplemental screening US. Further large-scale, multicenter, prospective studies are needed to validate the effectiveness of the downgrade criteria.