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Impact of breast density on cancer detection: observations from digital mammography test sets

International Journal of Radiology & Radiation Therapy
Kriscia A Tapia,1 Mary T Rickard,1,2 Mark F McEntee,1,3 Gail Garvey,1,4 Lorraine Lydiard,5 Patrick C Brennan,1


Introduction:The aim of this study is to investigate the impact of breast density on the diagnostic efficacy of 273 breast screening radiologists reading 1 of 5 test sets of digital mammograms within the BREAST program.

Methods:Retrospective data was collected from two hundred and seventy-three breast screening radiologists who participated in BREAST test sets between 2012 and 2017. Radiologists reviewed one of five test sets (labeled T1-T5) each containing 60 digital mammographic cases with 20 cancers and 40 normal cases. The cases also had varying mammographic densities based on BI-RADS density ratings. Cases were grouped into low-density (LD) and high-density (HD), and sensitivity, lesion sensitivity, specificity, receiver operating characteristic (ROC) and jackknifing free response operating characteristic (JAFROC) figures of merit were compared using Mann-Whitney U or unpaired t-tests.

Results:Readers in three out of five test sets showed better case sensitivity and lesion sensitivity in LD compared with HD cases (T2, T4, and T5: P≤0.001). One out of five test sets showed the same trend with specificity (T4: P<0.0001) and another set followed this pattern for ROC (T5: P<0.0001) and JAFROC (T5: P<0.0001) values. One test set (T3) demonstrated better performance in HD versus LD cases (ROC P<0.0001 and JAFROC P<0.0001). Reader experience, training, and set features may account for the variation in the results between the test sets.

Conclusion: Overall, radiologists taking the BREAST test sets perform better on cases with low mammographic density thus highlighting diagnostic advantage for women with lower breast density and reiterating the challenges presented by mammograms of dense breasts.


breast imaging, mammography, breast cancer, breast density, clinical radiology