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Accurate estimation of age-specific risk for breast and ovarian cancer can facilitate counseling of BRCA mutation carriers. Investigators followed women enrolled in familial cancer registries primarily in the U.K., Holland, and France. Women were recruited into this cohort from 1997 to 2011 and had not undergone risk-reducing breast or gynecologic surgery; follow-up continued until 2013 (median, 5 years). A total of 6036 BRCA1 and 3820 BRCA2 mutation carriers were followed (median age at study entry, 38).
Cumulative risk for breast cancer by age 80 was 72% in BRCA1 carriers and 69% in BRCA2 carriers; for ovarian cancer, cumulative risk was 44% and 17%, respectively. Peak breast cancer incidence occurred at age 41–50 for BRCA1 carriers (28 per 1000 person-years) and age 51–60 (31 per 1000) for BRCA2 carriers. Incidence of ovarian cancer was 3.6 times higher among BRCA1 than BRCA2 carriers, with peak incidence occurring among women aged 61–70 regardless of mutation type. Cumulative risk of contralateral breast cancer 20 years after the first breast cancer diagnosis was 40% for BRCA1 carriers and 26% for BRCA2 carriers. For both BRCA1 and BRCA2 carriers, breast cancer risk rose with the number of first- and second-degree relatives with breast cancer. In contrast, ovarian cancer risk did not vary by family history.
Kuchenbaecker KB et al. Risks of breast, ovarian, and contralateral breast cancer for BRCA1 and BRCA2 mutation carriers. JAMA 2017 Jun 20; 317:2402. (http://jamanetwork.com/journals/jama/article-abstract/2632503)
Comment
As most participants in this cohort study were “previvors” (i.e., had no history of cancer) who were identified with screening performed because of family history, these risk estimates should be generally useful for BRCA carriers identified in the course of such testing. In particular, these findings can inform decisions about surveillance and risk-reduction strategies (including chemoprevention and surgery) for these high-risk women.