Breast cancer risk inBRCA1/2mutation carriers and noncarriers under prospective intensified surveillance

Comparably little is known about breast cancer (BC) risks in women from families tested negative forBRCA1/2mutations despite an indicative family history, as opposed toBRCA1/2mutation carriers. We determined the age-dependent risks of first and contralateral breast cancer (FBC, CBC) both in noncarriers and carriers ofBRCA1/2mutations, who participated in an intensified breast imaging surveillance program. The study was conducted between January 1, 2005, and September 30, 2017, at 12 university centers of the German Consortium for Hereditary Breast and Ovarian Cancer. Two cohorts were prospectively followed up for incident FBC (n= 4,380; 16,398 person-years [PY], median baseline age: 39 years) and CBC (n= 2,993; 10,090 PY, median baseline age: 42 years). Cumulative FBC risk at age 60 was 61.8% (95% CI 52.8-70.9%) forBRCA1mutation carriers, 43.2% (95% CI 32.1-56.3%) forBRCA2mutation carriers and 15.7% (95% CI 11.9-20.4%) for noncarriers. FBC risks were significantly higher than in the general population, with incidence rate ratios of 23.9 (95% CI 18.9-29.8) forBRCA1mutation carriers, 13.5 (95% CI 9.2-19.1) forBRCA2mutation carriers and 4.9 (95% CI 3.8-6.3) forBRCA1/2noncarriers. Cumulative CBC risk 10 years after FBC was 25.1% (95% CI 19.6-31.9%) forBRCA1mutation carriers, 6.6% (95% CI 3.4-12.5%) forBRCA2mutation carriers and 3.6% (95% CI 2.2-5.7%) for noncarriers. CBC risk in noncarriers was similar to women with unilateral BC from the general population. Further studies are needed to confirm whether less intensified surveillance is justified in women fromBRCA1/2negative families with elevated risk.