Women who are diagnosed with breast cancer before age 55 and have a first-degree family history of bilateral disease have risks of contralateral breast cancer similar to women with deleterious mutations of BRCA1 and BRCA2, according to a study recently published in the Journal of Clinical Oncology, by Anne S. Reiner, MPH, of Memorial Sloan-Kettering Cancer Center, New York, and colleagues.
“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,” the investigators concluded. “Because women with a family history of bilateral breast cancer have risks of [contralateral breast cancer] similar to those of mutation carriers, these women should receive counseling for preventive measures.”
The study involved 594 patients with contralateral breast cancer and 1,119 controls with unilateral breast cancer who tested negative for BRCA1 and BRCA2 mutations. The women were selected from the WECARE study, a population-based case control study that identifies patients with contralateral or unilateral breast cancer through four cancer registries in the United States and though the Danish Breast Cancer Cooperative Group Registry, supplemented by data from the Danish Cancer Registry.
“A first-degree family history of breast cancer was defined as a diagnosis of breast cancer in at least one first-degree relative (ie, mother, sister, or daughter),” the researchers explained. The investigators estimated age-specific and family history–specific 10-year cumulative absolute risks of contralateral breast cancer.
Family history of breast cancer was associated with an increased risk of contralateral breast cancer, the researchers reported. That risk was highest among women < 45 years with first-degree relatives who were also affected when they were < 45 years (rate ratio = 2.5; 95% confidence interval [CI] = 1.1–5.3) or among women with first-degree relatives with bilateral disease (rate ratio = 3.6; 95% CI = 2.0–6.4).
Women diagnosed with unilateral breast cancer before age 55 with a first-degree family history of bilateral disease had a 10-year contralateral breast cancer risk of 15.6%, the investigators stated. This risk is “nearly as high as that of women who are BRCA1 or BRCA2 mutation carriers (15.6% vs 18.4%, respectively),” the researchers reported.
“It is important to note that other studies have found higher 10-year rates of [contralateral breast cancer] for BRCA carriers in the 30% to 40% range. However, these studies often differ from the current study by using even younger women or including just BRCA1 carriers. We elected to compare results produced from the same population to take advantage of all similarities including study design and patient case ascertainment,” the investigators noted. ■
Reiner AS, et al: J Clin Oncol, December 26, 2012 (early release online).