Genetic assessment of hereditary breast and ovarian cancer in the Harris Health System: A five-year, single-center experience.

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10587 Background: Identifying patients with hereditary breast cancer is critical since lifetime breast cancer risk is as high as 85% for those with germline BRCA1/2 mutations and preventive interventions can reduce that risk. However, genetic assessments and counseling are often underutilized among racial/ethnic minority populations. Reducing this genetic testing gap is important since hereditary breast/ovarian cancer syndromes occur among racial/ethnic minorities at least as frequently as non-Ashkenazi Jewish, non-Hispanic White populations. More information on variants in these populations is also needed to better define their genetic susceptibility. Methods: We conducted a retrospective study of adult patients evaluated for genetic testing for hereditary breast/ovarian cancer by a genetic counselor between October 1, 2009 and September 30, 2014 in Harris Health System which is a large, county health system composed mostly of underserved and minority patients. Data from 2015-2019 is currently being extracted and we are reporting the first 5 years of data. Descriptive statistics were used to summarize patient data. Results: 659 patients underwent genetic counseling (10.5% non-Hispanic White, 24.4% Black, 56.9% Hispanic, 5.9% Asian, and 2.3% other). Five patients had Ashkenazi Jewish ancestry. The majority of patients completed testing (87.4%) with 72.7% receiving financial assistance. Among those who did not complete testing, only 12.0% declined, while 66.3% did not meet guideline-based criteria or were recommended to have an affected relative tested. Multigene panel testing was not available until April 2014, so most underwent BRCA sequencing (75.0%) and/or a BRCA large rearrangement test (61.0%). 36.1% received multigene panel testing, 4.6% single site analysis, and 4.4% p53 sequencing. Deleterious mutations occurred in 98 (14.9%) patients: BRCA1 (n = 60), BRCA2 (n = 25), PALB2 (n = 7), ATM (n = 3), and other (n = 3). The distribution of races/ethnicities among those with deleterious mutations was similar to the overall population (7.1% non-Hispanic White, 18.4% Black, 69.4% Hispanic, 3.1% Asian, and 2.0% other). 80.6% of those with deleterious mutations had breast cancer. High rates of bilateral mastectomies were performed in patients with deleterious mutations: BRCA1 60%, BRCA2 55%, PALB2 57.1%, and ATM 33%. Risk-reducing salpingectomy or salpingo-oophorectomy was performed in 56.7% BRCA1, 60% BRCA2, 28.5% PALB2, and 33.3% other mutation carriers. Conclusions: We demonstrate that with the support of financial assistance programs, most patients who receive genetic counseling will accept genetic testing in a socioeconomically underserved, racially/ethnically diverse population. Identification of high-risk patients in these groups is critical since pathogenic variants in this population were common and more than half underwent risk-reducing procedures.