Abstract
BACKGROUND: Guidelines from the American Cancer Society recommend annual breast magnetic resonance imaging (MRI) screening for women with a projected lifetime risk of ≥20% based on risk models that use family history. Because MRI screening is costly and has limited specificity, estimates of the numbers of U.S. women with ≥20% breast cancer risk would be useful. METHODS: We used data from the 2000 and 2005 National Health Interview Survey and the National Cancer Institute (NCI) Breast Cancer Risk Assessment Tool (i.e., Gail model 2 with a revision for African Americans) to calculate estimates of U.S. women by age and race/ethnicity categories with a lifetime absolute breast cancer risk of ≥20%. Distributions of 5-year and lifetime absolute risk of breast cancer were compared across demographic groups. RESULTS: We estimated that 1.09% (95% confidence interval, 0.95-1.24%) of women age 30 to 84 years have a lifetime absolute breast cancer risk of ≥20%, which translates to 880,063 U.S. women eligible for MRI screening. The 5-year risks are highest for white non-Hispanics and lowest for Hispanics. The lifetime risks decrease with age and are generally highest for white non-Hispanics, lower for African American non-Hispanic, and lowest for Hispanics. CONCLUSION: We provide national estimates of the number of U.S. women who would be eligible for MRI breast screening and distributions of 5-year and lifetime risks of breast cancer using the NCI Breast Cancer Risk Assessment Tool. IMPACT: These estimates inform the potential resources and public health demand for MRI screening and chemopreventive interventions that might be required for U.S. women.