In a study reported in JAMA Internal Medicine, Kerlikowske et al found that the combined use of Breast Imaging Reporting and Data System (BI-RADS) breast density and Breast Cancer Surveillance Consortium (BCSC)-defined risk for breast cancer may be an effective way of identifying women with dense breasts at high risk for advanced cancer who require discussion of need for supplemental imaging.
This prospective cohort study assessed 638,856 women aged 40 to 74 years who had 1,693,163 screening digital mammograms taken at BCSC imaging facilities between January 2005 and December 2014. Advanced breast cancer was defined as stage IIB or higher diagnosed within 12 months of screening mammography. High advanced cancer rates were defined as ≥ 0.61 cases per 1,000 mammograms, representing the top 25th percentile of advanced cancer rates.
Overall, women with heterogeneously or extremely dense breasts on BI-RADS accounted for 47.0% of screened women and 60.0% of advanced cancers. High advanced cancer rates were found in women with BI-RADS heterogeneously dense breasts and BCSC 5-year risk of ≥ 2.5% (accounting for 6.0% of screened women) and women with extremely dense breasts and 5-year risk of ≥ 1.0% (accounting for 6.5% of screened women); these density-risk subgroups accounted for 12.5% of screened women and 27.1% of advanced cancers.
Advanced cancer rates of ≥ 0.51 cases per 1,000 mammograms occurred in the density-risk subgroups of scattered fibroglandular density or heterogeneously dense breasts and BCSC 5-year risk of ≥ 1.67%, and extremely dense breasts and 5-year risk of ≥ 1.00%, with these subgroups accounting for 32.7% of screened women and 54.7% of advanced cancers. Women with any BI-RADS density and 5-year risk < 1.0%, accounting for 29.5% of screened women, had the lowest advanced cancer rates and screen-detected early cancer rates.
With regard to density-age subgroups, high advanced cancer rates were observed in women with heterogeneously dense breasts between ages 60 to 74 years and women with extremely dense breasts between ages 50 to 69 years; these subgroups accounted for 16.4% of screened women and 27.6% of advanced cancers.
The investigators calculated that supplemental imaging in all women with dense breasts would result in a ratio of 1,866 supplemental imaging discussions per potential advanced cancer prevented. Supplemental imaging based on using the combination of density and BCSC 5-year risk to identify groups with high advanced cancer rates would reduce the ratio to 1,097 discussions per potential advanced cancer prevented.
The investigators concluded, “The findings suggest that breast density notification should be combined with breast cancer risk, so women at highest risk for advanced cancer are targeted for supplemental imaging discussions and women at low risk are not. BI-RADS breast density combined with BCSC 5-year risk may offer a more efficient strategy for supplemental imaging discussions than targeting all women with dense breasts.”
Karla Kerlikowske, MD, of the Department of Veterans Affairs, University of California, San Francisco, is the corresponding author for the JAMA Internal Medicine article.
Disclosure: The study was supported by the Patient-Centered Outcomes Research Institute (PCORI), Breast Cancer Surveillance Consortium, National Cancer Institute, Agency for Health Research and Quality, and Lake Champlain Cancer Research Organization. For full disclosures of the study authors, visit jamanetwork.com.
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