Breast and ovarian cancer risks in a large series of clinically ascertained families with a high proportion of BRCA1 and BRCA2 Dutch founder mutations

Background: BRCA1 or BRCA2 mutations confer increased risks of breast and ovarian cancer, but risks have been found to vary across studies and populations. Methods: We ascertained pedigree data of 582 BRCA1 and 176 BRCA2 families and studied the variation in breast and ovarian cancer risks using a modified segregation analysis model. Results: The average cumulative breast cancer risk by age 70 years was estimated to be 45% (95% CI 36 to 52%) for BRCA1 and 27% (95% CI 14 to 38%) for BRCA2 mutation carriers. The corresponding cumulative risks for ovarian cancer were 31% (95% CI 17 to 43%) for BR... Mehr ...