Impact of race/ethnicity on MammaPrint genomic assay risk and prognosis in early breast cancer: A National Cancer Data Base analysis

Abstract

Background

Black race is associated with poorer prognosis in hormone receptor (HR)–positive, HER2-negative early breast cancer (EBC). The impact of race/ethnicity on the risk distribution and prognostic information provided by the 70-gene MammaPrint assay was evaluated.

Methods

Women with HR-positive EBC with tumors up to 5 cm in size and zero to three involved lymph nodes, who were diagnosed between 2009 and 2018, and who had an available MammaPrint result were identified in the National Cancer Data Base (NCDB). t-tests and χ² tests were used to compare patient characteristics, whereas log-rank tests assessed differences in overall survival (OS) between racial/ethnic subgroups.

Results

Of the 6137 women included, 82.8% (n = 5084) were non-Hispanic White, 8.9% (n = 545) were non-Hispanic Black (NHB), 4.8% (n = 292) were Hispanic, and the remainder were other/unknown (n = 216). Of these women, 58.4% (n = 3587) were MammaPrint low risk and 41.6% (n = 2550) were MammaPrint high risk. NHB and Hispanic women were more likely to have a high-risk MammaPrint result (p < .001) than other racial/ethnic subgroups. Five-year OS was worse for the MammaPrint high-risk versus low-risk group (92.6% vs. 96.6%; p < .0001). There were no significant differences in OS on the basis of race/ethnicity in the MammaPrint low-risk (p = .34) or high-risk (p = .79) subgroups. However, Black race did not affect mortality in the overall population (hazard ratio, 1.15; 95% confidence interval, 0.84–1.58).

Conclusions

NHB and Hispanic women were more likely to have high-risk MammaPrint results in this NCDB cohort. Although there were no differences in survival by race/ethnicity in the MammaPrint low- and high-risk groups, these findings are limited by the lack of association between race/ethnicity and mortality in the overall population when adjusting for other clinicopathologic prognostic covariates.