Evaluating Hormone Therapy-associated Increases in Breast Density: Comparison Between Reported and Simultaneous Assignment of BI-RADS Categories, Visual Assessment, and Quantitative Analysis 1

Abstract

Changes in breast density, which are commonly associated with hormone replacement therapy (HRT) use, may imply changes in breast cancer risk. This study explores the ability of different methods to detect hormone replacement therapy (HRT)-associated increases in breast density. Between 1997 and 2001, 51 postmenopausal women were reported to have HRT-associated increases in breast density at our institution. Twenty postmenopausal women not reported to have an increase in density during the same period were selected as controls. Mammograms from date of report and earlier comparison were used. Breast Imaging Reporting and Data System (BI-RADS) density categories from both dates were obtained from the mammography report. Mammograms were reviewed at separate time points and density changes evaluated by assigning BI-RADS density categories, visual assessment, and computer-assisted quantitative analysis. Mammogram reports were not available for two patients. The remaining 49 women with reported HRT increases in density were included. Reported BI-RADS categories resulted in detection of 57%, simultaneous BI-RADS assignment in 61%, visual assessment in 100%, and quantitative assessment in 94% of women with HRT-associated increases in density. Reported BI-RADS category change was the only method that resulted in false-positive increases in density for control patients. Minimal HRT associated increases in density were the most difficult to detect, with 90% of these 21 cases not detected by simultaneous BI-RADS category assignment and 3 cases not detected by quantitative methods when defined as an increase of at least 5%. Visual and quantitative assessment best identified women with HRT-associated increases in density, including those with minimal increases. Simultaneous assignment of BI-RADS categories was considerably better than use of reported BI-RADS categories. This information may be helpful in guiding research design of studies evaluating changes in density from the HRT use.