(ChemotherapyAdvisor) – Women diagnosed with breast cancer before the age of 45 years with a family history of the disease have 2.5 times the risk of asynchronous contralateral breast cancer (CBC) if they test negative for deleterious mutations in BRCA1 and BRCA2 than other survivors of breast cancer, a report from the Women’s Environmental Cancer and Radiation Epidemiology (WECARE) study concluded in the Journal of Clinical Oncology online December 26.

“This risk varies with diagnosis age, family history of CBC, and degree of relationship to an affected relative,” noted corresponding author Anne S. Reiner, MPH, of Department of Epidemiology and Biostatistics at Memorial Sloan-Kettering Cancer Center, New York, NY. “This has important implications for the clinical management of patients with breast cancer with family history of the disease.”

The population-based case-control WECARE study is comparing women with CBC to those with unilateral breast cancer. From this study, the investigators based their analysis on 594 patient cases of CBC and 1,119 controls with unilateral breast cancer.

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Family history of breast cancer was found to be associated with increased risk of CBC, they reported, with the risk highest among women younger than 45 years of age with first-degree relatives affected at young ages (<45 years; rate ratio [RR] 2.5; 95% CI 1.1–5.3) or women with first-degree relatives with bilateral disease (RR 3.6; 95% CI 2.0–6.4).

The 10-year cumulative risk of CBC was nearly as high among women who were mutation noncarriers with a bilaterally affected first-degree relative as that of women who are BRCA1 or BRCA2 mutation carriers (15.6% vs 18.4%, respectively).

“These results underscore the critical importance of obtaining detailed family histories from all women diagnosed with breast cancer, regardless of BRCA1 and BRCA2 mutation carrier status,” Dr. Reiner stated. “Because women with a family history of bilateral breast cancer have risks of CBC similar to those of mutation carriers, these women should receive counseling for preventive measures.”