Is mammography adequate for screening BRCA mutation carriers with low breast density?

10014 Background: Several large observational studies have demonstrated that magnetic resonance imaging (MRI) is much more sensitive than M (sensitivity 71-96% vs. 28-43%) for screening women > age 25 at high risk for hereditary breast cancer. However, MRI is much more costly and less specific than M. The extent to which the low sensitivity of M in these studies is due to the greater average breast density of younger women is unknown. Accordingly, we sought to determine the sensitivity of M and MRI according to breast density for the detection of breast cancer in a screening study of BRCA mutation carriers.,Breast density was measured on the screening mammogram of the contralateral breast for all women who developed in-situ or invasive breast cancer on study. Density was measured in 2 ways: qualitatively according to the four categories characterized by the BIRADS system: 1) mostly fatty, 2) scattered fibroglandular tissue, 3) heterogeneously dense, 4) extremely dense; and semi-quantitatively using computer-aided techniques with subsequent classification as: A) ≤10%, B) 11-25%, C) 26%-50%, or D) >50% density.,Between 11/97 and 06/05 a total of 39 cases (12 in-situ and 27 invasive) were found in 36 mutation carriers (19 BRCA1 and 17 BRCA2). Mean age of the women with cancer was 48 (range 34 to 64). Average semi-quantitative breast density for BRCA1 mutation carriers was 28% and for BRCA2 was 27%. Sensitivity of M vs. MRI for in-situ cases was 25% vs. 83%, and for invasive cases was 30% vs. 93%. Sensitivities for BRCA1 and BRCA2 mutation carriers were similar. For BIRADS 1 to 4 respectively M detected 1/3 (33%), 5/11 (45%), 4/22 (18%), and 1/3 (33%) of cases; and for density groups A to D respectively detected 2/6 (33%), 7/15 (47%), 1/11 (9%) and, 1/7 (14%).,Although there was a trend towards decreasing mammographic sensitivity with increasing density, even among BRCA mutation carriers with low breast density mammography is an inadequate screening tool. No significant financial relationships to disclose.