Variation in Mammographic Breast Density Assessments Among Radiologists in Clinical Practice

Abstract

Background About half of US states currently require radiology facilities to disclose mammographic breast density to women, often with language recommending discussion of supplemental screening options for women with dense breasts. Objective To examine variation in breast density assessment across radiologists in clinical practice. Design Cross-sectional and longitudinal analyses of prospectively collected observational data. Setting Thirty radiology facilities within the three breast cancer screening research centers of the Population-based Research Optimizing Screening through Personalized Regimens (PROSPR) consortium. Participants Radiologists who interpreted ≥500 screening mammograms during 2011–2013 (N=83). Data on 216,783 screening mammograms from 145,123 woman aged 40–89 years were included. Measurements Mammographic breast density as clinically recorded using the four Breast Imaging-Reporting and Data System density categories (heterogeneously dense and extremely dense categories were considered “dense” for analyses); patient age, race, and body mass index (BMI). Results Overall, 36.9% of mammograms were rated as dense. Across radiologists, this percentage ranged from 6.3% to 84.5% (median 38.7%, interquartile range 22.0%), with multivariable adjustment for patient characteristics having little impact (interquartile range 20.9%). Examination of patient subgroups revealed that variation in density assessment across radiologists was pervasive in all but the most extreme patient age and BMI combinations. Among women undergoing consecutive exams interpreted by different radiologists, 17.2% (5,909/34,271) had discordant assessments of dense/non-dense status. Limitations Quantitative measures of mammographic breast density were not available for comparison. Conclusions There is wide variation in density assessment across radiologists that should be carefully considered by providers and policy makers when considering supplemental screening strategies. The likelihood of a woman being told she has dense breasts varies substantially according to which radiologist interprets her mammogram. Funding Source National Institutes of Health

Agreement between Breast Percentage Density Estimations from Standard-Dose versus Synthetic Digital Mammograms: Results from a Large Screening Cohort Using Automated Measures

“…Our work is timely, because the rapid implementation of sDM-DBT is occurring at the same time that breast density notification legislation has been passed in more than 50% of the United States, necessitating a reliable method of estimating density from synthetic images. The ability to reproducibly assess breast density independently of mammographic image type is important, as inconsistent breast density assessment could have implications for cancer risk assessment and also for whether it may be appropriate to pursue supplemental screening (21). We included a 4-month consecutive series of screening examinations for which every woman included had both sDM and standard-dose DM performed as part of their routine screening, providing a large sample to evaluate the consistency of breast density estimates between the two mammography image types and avoiding the biases inherent in a convenience sample.…”

“…The patient is then assigned to one of the four breast density categories by using the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) (18). However, visual breast density estimates are subjective and fraught with significant intra- and interobserver variability (19–21). To overcome this limitation, fully automated software algorithms have been developed to generate reproducible quantitative measures of breast density (22–25), several of which have shown associations with both breast cancer masking and breast cancer risk (26–28).…”

Risk-based Breast Cancer Screening

“…Fueled by patient advocacy groups, more than half of U.S. states have now adopted legislation requiring radiology facilities to disclose mammography breast density directly to women, many with language recommending that patients discuss options for supplemental screening with their physicians. 19,20 Connecticut was the first state to enact density reporting legislation in 2011, with some clinicians referring all patients with dense breasts for supplemental ultrasound in the first year after adoption. 21 National legislation is also currently under consideration, including a proposed amendment to the Public Health Service Act requiring notification of breast density to patients and stating that they may benefit from supplemental screening.…”

“…32 In one study of 30 U.S. facilities, assessments of dense breast made by 83 radiologists ranged from 6.3% to 84.5% of all mammograms interpreted by the radiologist, with multivariable adjustments for patient characteristics having little effect on the range of variation. 19 Moreover, from one screening mammogram to the next, 17% of women had discordant assessments with regards to having dense versus non-dense breasts, even though breast density likely changes much more gradually and over a longer period of time. 19 …”

“…19 Moreover, from one screening mammogram to the next, 17% of women had discordant assessments with regards to having dense versus non-dense breasts, even though breast density likely changes much more gradually and over a longer period of time. 19 …”