Long-term results of the Toronto magnetic resonance imaging (MRI) breast surveillance study of women with BRCA1 or BRCA2 mutations.

542 Background: Although the addition of MRI to mammography for breast cancer screening in women with BRCA mutations has been shown to significantly increase sensitivity, some groups have reported high interval cancer and node-positive rates for BRCA1 mutation carriers, and the impact on survival is unknown. We report screening performance, cancer stage, distant recurrence rate, and breast cancer-specific mortality for women with BRCA mutations enrolled in our MRI screening program. Methods: From 1997 to 2009, 496 women ages 25 to 65 (median 44) with a BRCA1(54%) or BRCA2 (46%) mutation, 380 with no previous cancer, were enrolled in a prospective screening trial that included annual breast MRI and mammography. Women underwent a total of 1847 screening rounds (median 3, range 1-9). Results: 57 cancers were identified (53 detected at screening, 1 interval, and 3 incidental at prophylactic mastectomy), of which 37 (65%) were invasive. Sensitivity of MRI vs. mammography was 86% vs. 19% overall (p<0.0001), 74%...