BRCA1-Associated Breast Cancers Present Differently From BRCA2-Associated and Familial Cases:Long-Term Follow-Up of the Dutch MRISC Screening Study

PurposeThe Dutch MRI Screening Study on early detection of hereditary breast cancer started in 1999. We evaluated the long-term results including separate analyses of BRCA1 and BRCA2 mutation carriers and first results on survival.Patients and MethodsWomen with higher than 15% cumulative lifetime risk (CLTR) of breast cancer were screened with biannual clinical breast examination and annual mammography and magnetic resonance imaging (MRI). Participants were divided into subgroups: carriers of a gene mutation (50% to 85% CLTR) and two familial groups with high (30% to 50% CLTR) or moderate risk (15% to 30% CLTR).ResultsOur update contains 2,157 eligible women including 599 mutation carriers (median follow-up of 4.9 years from entry) with 97 primary breast cancers detected (median follow-up of 5.0 years from diagnosis). MRI sensitivity was superior to that of mammography for invasive cancer (77.4% v 35.5%; P <.00005), but not for ductal carcinoma in situ. Results in the BRCA1 group were worse compared to the BRCA2, the high-, and the moderate-risk groups, respectively, for mammography sensitivity (25.0% v 61.5%, 45.5%, 46.7%), tumor size at diagnosisConclusionScreening results were somewhat worse in BRCA1 mutation carriers, but 6-year survival was high in all risk groups.