Abstract
Since 2008, the Iwate Cancer Society has been implementing a third-reader system in which a third reader makes the final judgment when the first and second readers offer different interpretations of screening mammography images.
In this study, 351,134 women aged ≥40 years who underwent screening mammography (alone or with palpation) at the Iwate Cancer Society between 2008 and 2018 were included. Of the 7,282 third readings performed, 6,154(84.5%) were judged as not requiring further detailed examination.
If a third reading was not performed, the recall rate was 4.1%, but finally, the results showed a recall rate of 2.4%, breast cancer detection rate of 0.27%, and a positive predictive value of 11.5%. In addition, third readings had not been performed for interval breast cancer until 2020. Of the 3,433 women for whom a third reading was performed during the period between 2014 and 2018,2,669 and 764 were judged by the first and second readers, respectively, as requiring further detailed examination. Of the cases judged by the second and first readers, 369(48.3%) and 227(8.5%), respectively, were judged as requiring further detailed examination by the third reader. Of the 84 cases of breast cancer diagnosed, 70(83%) were diagnosed by the second reader, while only 14(17%) were diagnosed by the first reader, with PPVs of 9.2% and 0.5%, respectively.
Some kind of intervention is needed for cases with discrepant judgement between the first and second readers, and one of the potentially promising is the use of a third-reader system.
