Impact of the second reader on screening outcome at blinded double reading of digital screening mammograms

To determine the impact of the second reader on screening outcome at blinded double reading of digital screening mammograms.

We included a consecutive series of 99,013 digital screening mammograms, obtained between July 2013 and January 2015 and double read in a blinded fashion. During 2-year follow-up, we collected radiology, surgery and pathology reports of recalled women.

Single reading resulted in 2928 recalls and 616 screen-detected cancers (SDCs). The second reader recalled another 612 women, resulting in 82 additional SDCs. Addition of the second reader increased the recall rate (3.0% to 3.6%, p < 0.001), cancer detection rate (6.2-7.0 per 1000 screens, p < 0.001) and false positive recall rate (24.4-28.7 per 1000 screens, p < 0.001). Positive predictive value of recall (21.0% vs. 19.7%, p = 0.20) and of biopsy (52.1% vs. 50.9%, p = 0.56) were comparable for single reading and blinded double reading. Tumour characteristics were comparable for cancers detected by the first reader and cancers additionally detected by the second reader, except of a more favourable tumour grade in the latter group.

At blinded double reading, the second reader significantly increases the cancer detection rate, at the expense of an increased recall rate and false positive recall rate.