Effect of integrating 3D-mammography (digital breast tomosynthesis) with 2D-mammography on radiologists' true-positive and false-positive detection in a population breast screening trial.

Objective: We investigated the effect of integrating three-dimensional (3D)-mammography with 2D-mammography on radiologists' detection measures in the 'screening with tomosynthesis or standard mammography' (STORM) trial.

Methods: STORM, a prospective population-based trial (Trento and Verona breast screening services) compared sequential screen-reading: 2D-mammography alone and integrated 2D/3D-mammography. Radiologist-specific detection measures were calculated for each screen-reading phase for eight radiologists: number of detected cancers, proportion of true-positive (TP) detection, and number and rate of false-positive (FP) recalls (FPR). We estimated the incremental cancer detection rate (CDR).

Results: There were 59 cancers and 395 false recalls amongst 7292 screening participants. At 2D-mammography screening, radiologist-specific TP detection ranged between 38% and 83% (median 63%; mean 60% and sd 15.4%); at integrated 2D/3D-mammography, TP detection ranged between 78% and 93% (median 87%; mean 87% and sd 5.2%). For all but one radiologist, 2D/3D-mammography improved breast cancer detection (relative to 2D-mammography) ranging between 0% and 54% (median 29%; mean 27% and sd 16.2%) increase in the proportion of detected cancers. Incremental CDR attributable to integrating 3D-mammography in screening varied between 0/1000 and 5.3/1000 screens (median 1.8/1000; mean 2.3/1000 and sd 1.6/1000). Radiologist-specific FPR for 2D-mammography ranged between 1.5% and 4.2% (median 3.1%; mean 2.9% and sd 0.87%), and FPR based on the integrated 2D/3D-mammography read ranged between 1.0% and 3.3% (median 2.4%; mean 2.2% and sd 0.72%). Integrated 2D/3D-mammography screening, relative to 2D-mammography, had the effect of reducing FP and increasing TP detection for most radiologists.

Conclusion: There was broad variability in radiologist-specific TP detection at 2D-mammography and hence in the additional TP detection and incremental CDR attributable to integrated 2D/3D-mammography; more consistent (less variable) TP-detection estimates were observed for the integrated screen-read. Integrating 3D-mammography with 2D-mammography improves radiologists' screen-reading through improved cancer detection and/or reduced FPR, with most readers achieving both using integrated 2D/3D mammography.