BRCA1/2 Mutations Up Risk of Contralateral Breast Cancer

For mutation carriers, age at diagnosis and triple-negative first tumor also impact risk

THURSDAY, Dec. 8 (HealthDay News) -- Women who have had unilateral breast cancer and carry BRCA1/2 genetic mutations have a higher risk of developing contralateral breast cancer (CBC), according to a study presented at the annual San Antonio Breast Cancer Symposium, held from Dec. 6 to 10.

Alexandra J. van den Broek, from the Netherlands Cancer Institute in Amsterdam, and colleagues investigated the effect of BRCA1/2-carriership, and its correlation with other factors, on the risk of developing CBC in 4,856 high-risk women with unilateral, invasive breast cancer. Between 1970 and 2003, data were collected on patients diagnosed under the age of 50 years. Patients were followed up for a median of 9.8 years.

The investigators found that 4.2 percent of patients genotyped for BRCA1/2 mutations were carriers. A total of 9 percent of the patients developed CBC, giving a cumulative 15-year risk of 10.4 percent for non-carriers and 35.4 percent for carriers (hazard ratio [HR], 4.04). The cumulative 15-year risk for carriers was 52.4 percent for patients diagnosed with their first breast cancer under the age of 40, and 21.3 percent for patients diagnosed over the age of 40 (HR for age over 40, 0.30). The cumulative risk for carriers was 43.6 percent for a triple negative first tumor and 13.4 percent for a non-triple negative first tumor (HR for non-triple negative first tumor, 0.24). For non-carriers, age at diagnosis and triple negative status did not predict the risk of CBC.

"Guidelines about treatment decisions and screening for follow-up should take into account these high-risk subgroups to provide even better information and counseling for BRCA1/2 mutation carriers," the authors write.

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