Purpose: To compare the effectiveness of mammography, breast ultrasound, and magnetic resonance imaging (MRI) for surveillance of women at increased familial risk for breast cancer (lifetime risk of 20% or more).
Patients and methods: We conducted a surveillance cohort study of 529 asymptomatic women who, based on their family history and/or mutational analysis, were suspected or proven to carry a breast cancer susceptibility gene (BRCA). A total of 1,542 annual surveillance rounds were completed with a mean follow-up of 5.3 years. Diagnostic accuracies of the three imaging modalities used alone or in different combinations were compared.
Results: Forty-three breast cancers were identified in the total cohort (34 invasive, nine ductal carcinoma-in-situ). Overall sensitivity of diagnostic imaging was 93% (40 of 43 breast cancers); overall node-positive rate was 16%, and one interval cancer occurred (one of 43 cancers, or 2%). In the analysis by modality, sensitivity was low for mammography (33%) and ultrasound (40%) or the combination of both (49%). MRI offered a significantly higher sensitivity (91%). The sensitivity of mammography in the higher risk groups was 25%, compared with 100% for MRI. Specificity of MRI (97.2%) was equivalent to that of mammography (96.8%).
Conclusion: Mammography alone, and also mammography combined with breast ultrasound, seems insufficient for early diagnosis of breast cancer in women who are at increased familial risk with or without documented BRCA mutation. If MRI is used for surveillance, diagnosis of intraductal and invasive familial or hereditary cancer is achieved with a significantly higher sensitivity and at a more favorable stage.