BRCA1 and BRCA2 Mutation Testing in Young Women With Breast Cancer.

IMPORTANCE: BRCA testing is recommended for young women diagnosed as having breast cancer, but little is known about decisions surrounding testing and how results may influence treatment decisions in young patients.
OBJECTIVES: To describe the use of BRCA testing and to evaluate how concerns about genetic risk and use of genetic information affect subsequent treatment decisions in young women with breast cancer. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional analysis of data collected following the opening of the study to accrual from October 10, 2006, through December 31, 2014, as part of the Helping Ourselves, Helping Others: Young Women's Breast Cancer Study, an ongoing prospective cohort study. Study participants included 897 women aged 40 years and younger at breast cancer diagnosis from 11 academic and community medical centers. MAIN OUTCOMES AND MEASURES: Frequency and trends in the use of BRCA testing and how genetic information is used to make treatment decisions among women who test positive vs negative for a BRCA mutation.
RESULTS: A total of 780 (87.0%) of 897 women reported BRCA testing by 1 year after breast cancer diagnosis (mean age at diagnosis, 35.3 vs 36.9 years for untested women; P < .001), with the frequency of testing increasing among women diagnosed from August 1, 2006, through December 31, 2013. Of 39 women who were diagnosed as having breast cancer in 2006, 30 (76.9%) reported testing. In 2007, a slightly lower percentage of women (87 of 124 [70.2%]) reported testing; however, the proportion tested increased each subsequent year, with 141 (96.6%) of 146 and 123 (95.3%) of 129 women diagnosed as having breast cancer in 2012 and 2013, respectively, reporting BRCA testing (P < .001). Among untested women, 37 (31.6%) of 117 did not report discussion of the possibility that they might have a mutation with a physician and/or genetic counselor, and 43 (36.8%) of 117 were thinking of testing in the future. A total of 248 (29.8%) of 831 women said that knowledge or concern about genetic risk influenced treatment decisions; among these women, 76 (86.4%) of 88 mutation carriers and 82 (51.2%) of 160 noncarriers chose bilateral mastectomy (P < .001). Fewer women reported that systemic treatment decisions were influenced by genetic risk concern. CONCLUSIONS AND RELEVANCE: Rates of BRCA1 and BRCA2 mutation testing are increasing in young women with breast cancer. Given that knowledge and concern about genetic risk influence surgical decisions and may affect systemic therapy trial eligibility, all young women with breast cancer should be counseled and offered genetic testing, consistent with the National Comprehensive Cancer Network guidelines.