Abstract P2-09-09: Genetic assessment of hereditary breast and ovarian cancer in the Smith Clinic: A 10-year, single center experience

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Abstract Background: Highly penetrant pathogenic variants causing hereditary breast and ovarian cancer syndrome occur among patients of racial/ethnic minorities at least as frequently as they do among non-Ashkenazi Jewish, non-Hispanic White patients. However, studies suggest that disparities persist in genetic counseling and testing in these populations. It is critical that we reduce the testing gap to better understand genetic susceptibility in minority patients and identify individuals who may benefit from preventive and therapeutic interventions. We explore genetic counseling and testing outcomes in a safety net system with significant support from financial assistance programs that minimizes typical financial and insurance barriers. Methods: This is a retrospective study of adult patients evaluated by a genetic counselor for hereditary breast/ovarian cancer syndrome between October 1, 2009 and September 30, 2019 in Smith Clinic, which is part of a large, county hospital system serving predominantly racial/ethnic minority and uninsured or under-insured patients, and affiliated with the Dan L Duncan Comprehensive Cancer Center. All patients between October 1, 2009 and February 28, 2013 underwent genetic testing, whereas all patients after March 1, 2013 were evaluated by a genetic counselor but may not have completed testing. Patient clinical data was summarized using descriptive statistics. Results: 1,682 patients (mean age at time of counseling/testing 48.2 years) were evaluated by a genetic counselor. Patient-reported race/ethnicity was 58.7% Hispanic, 25.2% non-Hispanic Black (NHB), 8.8% non-Hispanic White (NHW), 4.6% Asian, and 2.7% other with 2.6% having some Native American and 0.6% having any Ashkenazi Jewish genealogic ancestry. Among the 1,397 patients who completed genetic testing, 76.2% received financial assistance. The majority were tested with a multigene panel (70.4%) with the remaining primarily undergoing BRCA sequencing or BRCA large rearrangement test (multigene panels not available until April 2014). More than three-quarters of patients who did not complete testing (n=285, 20.6% of those evaluated after March 1, 2013) did not meet guideline-based criteria or had a relative who was a more appropriate candidate for testing. Only 10.2% declined testing with rates of decline highest among NHB patients. A pathogenic mutation was found in 15.4% of individuals tested: BRCA1 (n=108), BRCA2 (n=57), PALB2 (n=26), ATM (n=8), other (n=18). Rates of pathogenic mutations were higher among NHW and Hispanic patients (NHW 14.9%, Hispanic 17.4%, NHB 11.3%, Asian 9.0%, Other 17.1%). The relatively high percentages of identified pathogenic mutations was likely related to the fact that 84.1% of patients were referred for a personal history of breast and/or ovarian cancer with 6.1% of NHW and 5.7% of Hispanic patients referred for a relative with or personal history of a known pathogenic mutation. Among those with BRCA1/2 or PALB2 mutations, risk-reducing procedures were frequent among all races except those classified as other (mastectomies: NHW 50%, NHB 45.5%, Hispanic 51.9%, Asian 40%, other 16.7%; salpingo-oophorectomies or salpingectomies: NHW 35.7%, NHB 45.5%, Hispanic 56.4%, Asian 60%, other 16.7%). Conclusions: In a racially/ethnically diverse, low-income population, genetic testing uptake is high when supported by financial assistance programs and an on-site genetic counselor. Regardless, reasons for declining testing warrant further exploration, particularly among non-Hispanic Black patients, to further reduce disparities in testing. Prompt referral of patients who meet testing guidelines for genetic evaluation is also critical since pathogenic mutations were frequently identified in all racial/ethnic subgroups and nearly half underwent a risk-reducing procedure. Citation Format: Nicole Higashiyama, Shaun Bulsara, Susan Hilsenbeck, Tiffaney Tran, Ria Brown, Mary Fang, Cathy Sullivan, Georgiann Garza, Maryam Nemati Shafaee, C. Kent Osborne, Mothaffar Rimawi, Julie Nangia. Genetic assessment of hereditary breast and ovarian cancer in the Smith Clinic: A 10-year, single center experience [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-09-09.