Purpose: To prospectively determine cancer yield, callback and biopsy rates, and positive predictive value (PPV) of mammography, magnetic resonance (MR) imaging, and ultrasonography (US) in women at high risk for breast cancer.
Materials and methods: The study was approved by the institutional review board and was HIPAA compliant, and informed consent was obtained. We conducted a prospective pilot study of screening mammography, MR, and US in asymptomatic women 25 years of age or older who were genetically at high risk, defined as BRCA1/BRCA2 carriers or with at least a 20% probability of carrying a BRCA1/BRCA2 mutation. All imaging modalities were performed within 90 days of each other. Data were analyzed by using exact confidence intervals (CIs) and the McNemar test.
Results: A total of 195 women were enrolled in this study over a 6-month period, and 171 completed all study examinations (mammography, US, and MR). Average age of the 171 participants was 46 years +/- 10.2 (standard deviation). Sixteen biopsies were performed and six cancers were detected, for an overall 3.5% cancer yield. MR enabled detection of all six cancers; mammography, two; and US, one. The diagnostic yields for each test were 3.5% for MR, 0.6% for US, and 1.2% for mammography. MR, US, and mammography findings prompted biopsy in 8.2%, 2.3%, and 2.3% of patients, respectively. None of the pairwise comparisons were statistically significant. The PPV of biopsies performed as a result of MR was 43%.
Conclusion: Screening MR imaging had a higher biopsy rate but helped detect more cancers than either mammography or US. US had the highest false-negative rate compared with mammography and MR, enabling detection of only one in six cancers in high-risk women.