The relationship between missed breast cancers on mammography in a test-set based assessment scheme and real-life performance in a National Breast Screening Programme

This retrospective study determined whether a test-set based assessment scheme (PERFORMS) used in a national breast screening programme could be used to predict real-life performance by investigating if the number of cancers missed by mammography readers in real-life related to the number of cancers missed in the PERFORMS test-set and whether real-life reading volumes affected performance.

Data was obtained from consenting readers in the screening programme in England (NHSBSP) where double reading is standard. The rate of cancers missed by individual first readers but correctly identified by second readers was compared with the number of cancers missed in the PERFORMS test-set over a 3-year period. NHSBSP readers are required to interpret at least 1500 cases per year as a first reader, so results were compared between readers who exceeded this target and those that did not. Parametric and non-parametric correlations were calculated.

Amongst the 536 readers, there was a highly significant positive correlation between the real-life and PERFORMS test-set missed cancer metrics (Pearson Correlation = 0.228, n = 536, p < .0001, Spearman's rho = 0.265, n = 536, p < .0001). There was no significant difference in rates of missed cancers between the 452 readers who exceeded the 1500 first read per year target and those who did not (t(94.2) = -1.87, p = .0643, r = 0.19).

The use of a test-set based assessment scheme accurately reflects real-life mammography reading performance, indicating that it can be a useful tool in identifying poor reader performance.