BRCA1 and breast cancer: In a meta-analysis of such case-based studies, by age 70 years, in BRCA1 carriers breast cancer risk was 65% (95% CI 51–75%) and ovarian cancer risk was 39% (95% CI 22–51%), and in BRCA2 carriers breast cancer risk was 45% (95% CI 33–54%) and ovarian cancer risk was 11% (95% CI 4.1–18%) (Antoniou et al, 2003).