Automated volumetric analysis of mammographic density in a screening setting: Worse outcomes for women with dense breasts

Abstract

Purpose: To describe screening outcomes from BreastScreen Norway stratified by volumetric breast density (VBD). Materials and Methods: This retrospective study included data from 107 949 women aged 50–69 years (mean age 6 standard deviation, 58.7 years 6 5.6) who underwent 307 015 screening examinations from 2007 to 2015. Automated software classified mammographic density as nondense (VBD ,7.5%) or dense (VBD 7.5%). Rates and distributions of screening outcomes (recall, biopsy, screendetected and interval breast cancer, positive predictive values of recall and of needle biopsy, sensitivity, specificity, and histopathologic tumor characteristics) were analyzed and stratified by density. Tests of proportions, including propensity score and t tests, were used. Results: In 28% (87 021 of 307 015) of the screening examinations, the breasts were classified as dense. Recall rates for women with nondense versus dense breasts were 2.7% (5882 of 219 994) and 3.6% (3101 of 87 021); biopsy rates were 1.1% (2359 of 219 994) and 1.4% (1209 of 87 021); rates of screen-detected cancer were 5.5 (1210 of 219 994) and 6.7 (581 of 87 021) per 1000 examinations; and rates of interval breast cancer were 1.2 (199 of 165 324) and 2.8 (185 of 66 674) per 1000 examinations, respectively (P , .001 for all). Sensitivity was 82% (884 of 1083) for nondense breasts and 71% (449 of 634) for dense breasts, whereas specificity was 98% (160 973 of 164 440) and 97% (64 250 of 66 225), respectively (P , .001 for both). For screen-detected cancers, mean tumor diameter was 15.1 mm and 16.6 mm (P = .01), and lymph node–positive disease was found in 18% (170 of 936) and 24% (98 of 417) (P = .02) of women with nondense and dense breasts, respectively. Conclusion: Screening examinations of women with dense breasts classified by using automated software resulted in higher recall rate, lower sensitivity, larger tumor diameter, and more lymph node–positive disease compared with women with nondense breasts.