Early use of clinical BRCA1/2 testing: associations with race and breast cancer risk

When BRCA1/2 testing became commercially available in 1996, many U.S. experts voiced concern about the potential for indiscriminate use of testing among low-risk women. Supporting this concern, several early surveys of interest in genetic testing suggested that genetic testing for cancer susceptibility might appeal most to individuals at low risk of carrying a mutation. To identify factors associated with early use of clinical BRCA1/2 testing, a case-control study was conducted at a large academic health system in the metropolitan Philadelphia region. A total of 167 women underwent genetic counseling for clinical BRCA1/2 testing between 1996 and 1997 (cases) compared with 138 women who were seen in faculty general internal medicine practices over the same period (controls). In this study we measured the risk factors for breast cancer, the risk factors for carrying a BRCA1/2 mutation, and sociodemographic characteristics. Use of BRCA1/2 counseling between 1996 and 1997 was positively associated with family but no personal history of breast cancer (odds ratio (OR), 22.4; 95% confidence interval (CI), 9.3-54.3); family and personal history of breast cancer (OR, 150.3; 95% CI, 24.1-939.6); being Caucasian and non-Jewish (OR, 4.1; 95% CI, 1.3-13.5); being Caucasian and Jewish (OR, 8.8; 95% CI, 2.2-35.5); and being married (OR, 3.2; 95% CI, 1.6-6.3). Use of BRCA1/2 counseling was inversely associated with increasing age (OR, 0.07; 95% CI, 0.02-0.28 for >60 compared to <50). As suggested by the association with family history, use of counseling was associated with having a higher predicted risk of breast cancer and a higher predicted risk of carrying a BRCA1 mutation (P < 0.0001). Women who sought clinical BRCA1/2 testing in the year after it became commercially available were not the "worried well," but women at significantly increased risk of carrying a mutation. However, even after adjusting for breast cancer risk, there was a substantial racial disparity in use of BRCA1/2 testing. These findings suggest that ensuring equal access to testing for high-risk individuals irrespective of race may be as important for the future of predictive genetic testing as restricting the use of testing among low-risk individuals.