Screening women at high risk for breast cancer with mammography and magnetic resonance imaging.

BACKGROUND: The authors compared the performance of screening mammography versus magnetic resonance imaging (MRI) in women at genetically high risk for breast cancer.

METHODS: The authors conducted an international prospective study of screening mammography and MRI in asymptomatic, genetically high-risk women age >/= 25 years. Women with a history of breast cancer were eligible for a contralateral screening if they had been diagnosed within 5 years or a bilateral screening if they had been diagnosed > 5 years previously. All examinations (MRI, mammography, and clinical breast examination [CBE]) were performed within 90 days of each other.

RESULTS: In total, 390 eligible women were enrolled by 13 sites, and 367 women completed all study examinations. Imaging evaluations recommended 38 biopsies, and 27 biopsies were performed, resulting in 4 cancers diagnosed for an overall 1.1% cancer yield (95% confidence interval [95%CI], 0.3-2.8%). MRI detected all four cancers, whereas mammography detected one cancer. The diagnostic yield of mammography was 0.3% (95%CI, 0.01-1.5%). The yield of cancer by MRI alone was 0.8% (95%CI, - 0.3-2.0%). The biopsy recommendation rates for MRI and mammography were 8.5% (95%CI, 5.8-11.8%) and 2.2% (95%CI, 0.1-4.3%).

CONCLUSIONS: Screening MRI in high-risk women was capable of detecting mammographically and clinically occult breast cancer. Screening MRI resulted in 22 of 367 of women (6%) who had negative mammogram and negative CBE examinations undergoing biopsy, resulting in 3 additional cancers detected. MRI also resulted in 19 (5%) false-positive outcomes, which resulted in benign biopsies.