Effect on sensitivity and specificity of mammography screening with or without comparison of old mammograms

In order to evaluate the effect of old mammograms on the specificity and sensitivity of radiologists in mammography screening, one hundred and fifty sets of screening mammograms were examined by 3 experienced screeners twice: once without and once in comparison with older mammograms. The films came from a population-based screening done during the first half of 1994 and comprised all 35 cancers detected during screening in 1994, 12/24 interval cancers, 14/34 cancers detected in the following screening and 89 normal mammograms. Without old mammograms, the screeners detected an average of 40.3 cancers (range 37-42), with a specificity of 87% (85-88%). With old mammograms, the screeners detected 37.7 cancers (range 34-42) with a specificity of 96% (94-99%). The change in detection rate was not significant. However, the increase in specificity was significant for each screener. Mammography screening with old mammograms available for comparison decreased the false-positive recall rate. The effect on sensitivity, however, was unclear