Adding MRI to mammography detects more cancers in women at high risk.
Even among women at highest risk for breast cancer (those with BRCA1 or BRCA2 mutations) who undergo regular screening mammography, substantial proportions develop invasive cancers. In a systematic review of 11 prospective studies (involving about 5000 patients), researchers assessed the accuracy of combining magnetic resonance imaging with mammography for screening such women.
Among biopsy-confirmed breast cancers, sensitivity for detecting lesions that were suspicious or highly suspicious and required biopsy (American College of Radiology Breast Imaging Reporting and Data System [BI-RADS] scores of 4 or 5) was 32% for mammography alone, 75% for MRI alone, and 84% (specificity, 95%) for the tests combined. Assuming a 2% pretest probability (i.e., prevalence) of breast cancer, probability of cancer after a negative test was 1.4% for mammography and 0.3% for MRI plus mammography, and probability of cancer after a positive test was 34% for mammography and 25% for MRI plus mammography.
Comment: False positives remain problematic with MRI screening. However, among women at high familial risk for breast cancer, our biggest challenge is detecting disease before it progresses. MRI, although not appropriate for universal screening of women at average risk, seems to improve cancer detection among women at high risk.
— Richard Saitz, MD, MPH, FACP, FASAM
Published in Journal Watch General Medicine July 8, 2008
Warner E et al. Systematic review: Using magnetic resonance imaging to screen women at high risk for breast cancer. Ann Intern Med 2008 May 6; 148:671.