Comparison of the Prevalence of Pathogenic Variants in Cancer Susceptibility Genes in Black Women and Non-Hispanic White Women with Breast Cancer in the United States

Importance: The prevalence of germline pathogenic variants (PVs) in cancer susceptibility genes in US Black women compared with non-Hispanic White women with breast cancer is poorly described. Objective: To determine whether US Black and non-Hispanic White women with breast cancer have a different prevalence of PVs in 12 cancer susceptibility genes. Design, Setting, and Participants: Multicenter, population-based studies in the Cancer Risk Estimates Related to Susceptibility (CARRIERS) consortium. Participants were Black and non-Hispanic White women diagnosed with breast cancer, unselected for family history or age at diagnosis. Data were collected from June 1993 to June 2020; data analysis was performed between September 2020 and February 2021. Main Outcomes and Measures: Prevalence of germline PVs in 12 established breast cancer susceptibility genes. Results: Among 3946 Black women (mean [SD] age at diagnosis, 56.5 [12.02] y) and 25287 non-Hispanic White women (mean [SD] age at diagnosis, 62.7 [11.14] y) with breast cancer, there was no statistically significant difference by race in the combined prevalence of PVs in the 12 breast cancer susceptibility genes evaluated (5.65% in Black vs 5.06% in non-Hispanic White women; P =.12). The prevalence of PVs in CHEK2 was higher in non-Hispanic White than Black patients (1.29% vs 0.38%; P <.001), whereas Black patients had a higher prevalence of PVs in BRCA2 (1.80% vs 1.24%; P =.005) and PALB2 (1.01% vs 0.40%; P <.001). For estrogen receptor-negative breast cancer, the prevalence of PVs was not different except for PALB2, which was higher in Black women. In women diagnosed before age 50 years, there was no difference in overall prevalence of PVs in Black vs non-Hispanic White women (8.83% vs 10.04%; P =.25), and among individual genes, only CHEK2 PV prevalence differed by race. After adjustment for age at diagnosis, the standardized prevalence ratio of PVs in non-Hispanic White relative to Black women was 1.08 (95% CI, 1.02-1.14), and there was no longer a statistically significant difference in BRCA2 PV prevalence. Conclusions and Relevance: This large population-based case-control study revealed no clinically meaningful differences in the prevalence of PVs in 12 breast cancer susceptibility genes between Black and non-Hispanic White women with breast cancer. The findings suggest that there is not sufficient evidence to make policy changes related to genetic testing based on race alone. Instead, all efforts should be made to ensure equal access to and uptake of genetic testing to minimize disparities in care and outcomes..