In a cohort study reported in JAMA, Karla Kerlikowske, MD, and colleagues found that screening with digital breast tomosynthesis (DBT) vs digital mammography was not associated with a lower risk of interval invasive breast cancer and was associated with a reduced risk of diagnosis of advanced disease among women with extremely dense breasts who were at high risk for breast cancer.
Karla Kerlikowske, MD
The study involved data from 504,427 women aged 40 to 79 years who underwent 375,189 screening DBT and 1,003,900 screening digital mammography examinations from 2011 through 2018 at 44 U.S. Breast Cancer Surveillance Consortium (BCSC) sites, with follow-up for cancer diagnoses through 2019. The primary outcome measures were rates per 1,000 examinations of interval invasive cancer within 12 months of screening mammography, and advanced breast cancer (prognostic pathologic stage II or higher) within 12 months of screening mammography.
Key Findings
Interval invasive cancer rates per 1,000 examinations did not significantly differ for DBT vs digital mammography (0.57 vs 0.61, difference = −0.04, 95% confidence interval [CI] = −0.14 to 0.06, P = .43) in the entire cohort. No differences were observed across breast density categories or among women with BCSC 5-year risk < 1.67% (low to average risk) or BCSC 5-year risk of ≥ 1.67% (high risk) across breast density categories.
The advanced cancer rate per 1,000 examinations was lower with DBT vs digital mammography (0.36 vs 0.45, difference = −0.09, 95% CI = −0.18 to −0.01) in the entire cohort. However, no significant differences were observed among the 96.4% of the cohort with nondense or heterogeneously dense breasts or those with extremely dense breasts with low to average BCSC risk. Among the 3.6% of women with extremely dense breasts and high BCSC risk (13,291 examinations in the DBT group and 31,300 in the digital mammography group), the rates per 1,000 examinations were 0.27 vs 0.80 (difference = −0.53, 95% CI = −0.97 to −0.10).
The investigators concluded, “Screening with DBT vs digital mammography was not associated with a significant difference in risk of interval invasive cancer and was associated with a significantly lower risk of advanced breast cancer among the 3.6% of women with extremely dense breasts and at high risk of breast cancer. No significant difference was observed in the 96.4% of women with nondense breasts, heterogeneously dense breasts, or with extremely dense breasts not at high risk.”
Dr. Kerlikowske, of the Departments of Medicine and Epidemiology and Biostatistics, University of California, San Francisco, is the corresponding author for the JAMA article.
Disclosure: The study was funded by the Patient-Centered Outcomes Research Institute, National Cancer Institute, and others. For full disclosures of the study authors, visit jamanetwork.com.
