Incident round cancers: what lessons can we learn?

At the time of implementation of the National Health Service Breast Screening Programme a range of targets were set, and have since been updated. This study looks at a subset of cancers detected by screening - the incident round cancers - which are not currently identified and addressed by the targets. In our first incident round we screened 24838 women and detected 112 breast cancers in 111 women. On the basis of a two-stage retrospective evaluation of the prevalent round mammograms in these 111 women, we classified the prevalent mammograms as false negative 21 (19%), minimal signs 32 (28%) and new tumours 59 (53%). Analysis of the radiographic features revealed a disproportionate number with parenchymal deformity (21%) and asymmetry (17%) among the missed tumours when compared to all tumours detected by our screening programme (12% and < 1%, respectively). Identification and quantification of these incidence detected missed cancers could be incorporated into the Quality Assurance Data Set, and used as another performance indicator. Reviewing the mammograms proved a valuable teaching exercise and has allowed us to develop a test set of challenging mammograms.