Abstract PO3-08-04: Prevalence of BRCA1/2 mutations in an underrepresented population of women with breast cancer: Observations from the City of Hope INSPIRE study

Abstract Background: Because African American and Latina women have been less likely to undergo germline testing, it has been difficult to determine the prevalence of hereditary breast and ovarian cancer predisposition in these populations. Here we report the prevalence of BRCA1/2 mutation in patients with a breast cancer diagnosis from City of Hope’s (COH) INSPIRE (Implementing Next-generation Sequencing for Precision Intervention and Risk Evaluation) study. Methods: Patients with a history of any stage breast cancer (stage 0-IV), who were seen by a City of Hope physician at the Duarte or Upland campuses, were approached by a clinical research coordinator for participation in an institutional tissue biorepository project. Demographic information included age, race and ethnicity. Patients consent for this IRB-approved study to store tumor specimens for future research use and Invitae germline testing for 155 predisposition genes which is performed at no cost to the patient. Results: From 7/9/20 until 4/2023, 2413 women consented for participation and underwent germline testing. Mutations in BRCA1 were identified in 53 and BRCA2 in 65. Table 1 summarizes the prevalence of BRCA1/2 mutations according to race and ethnicity. Pathogenic variants in BRCA1 were identified in 22/742 (3.0%) of Hispanic women compared to 16/1552 (1.7%) non-Hispanics (p=0.046). BRCA2 mutations were comparable 16/742 (2.2%) Hispanics and 47/1505 (3%) non-Hispanics. Hispanic women with breast cancer were 2.49 times as likely as non-Hispanics to carry a pathogenic germline BRCA1 mutations than BRCA2 (p=0.026) Conclusion: The prevalence of BRCA1/2 mutations in the African American and Latina population is higher than what was observed in White women. These data provide additional support for the recommendation to perform germline testing in all women with breast cancer, regardless of race or ethnicity Prevalence of BRCA 1 and 2 mutations by Self-Reported Race and Ethnicity # Tested BRCA1 BRCA2 BRCA1 or 2 VUS/Negative Race Native American 15 0 1 (6.7%) 1 (6.7%) 14 (93.3%) Pacific Islander 8 0 0 0 8 (100%) Asian 367 5 (1.4%) 11 (3%) 16 (4.4%) 351 (95.6%) Black 136 7 (5.1%) 4 (2.9%) 11 (8.1%) 125 (91.9%) White 1675 37 (2.2%) 44 (2.6%) 81 (4.8%) 1594 (95.2%) Other 86 1 (1.2%) 4 (4.7%) 4* (4.7%) 82 (95.3%) Unknown 126 3 (2.4%) 1 (0.8%) 5 (3.2% 122 (96.8%) TOTAL 2413 53 (2.2%) 65 (2.7%) 117 (4.8%) 2296 (95.2%) Ethnicity Hispanic 742 22(3%) 16 (2.2%) 37* (5%) 705(95%) Non-Hispanic 1552 26(1.7%) 47(3%) 73(4.7%) 1479 (95.3%) Unknown 119 53(2.2%) 2(1.7%) 7(5.9%) 112(94.1%) TOTAL 2413 53(2.2%) 65(2.7%) 7(5.9%) 112(94.2%) * Patient had both BRCA1 and BRCA2 mutations Citation Format: Joanne Mortimer, Sydney Lindsey, Ilana Solomon, Wai Park, Duveen Sturgeon, Kathleen Blazer, Stacy Gray, Joseph Bonner, Xiaoyu Xia, Stephen Gruber. Prevalence of BRCA1/2 mutations in an underrepresented population of women with breast cancer: Observations from the City of Hope INSPIRE study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-08-04.