Somatic mutations of triple-negative breast cancer: a comparison between Black and White women

Understanding the contribution of tumor genome biology to racial disparities of triple-negative breast cancer (TNBC) is important for narrowing the cancer mortality gap between Black and White women.

We evaluated tumor somatic mutations using targeted sequencing of a customized panel of 151 genes and 15 copy number variations (CNVs) within a population of 133 TNBC patients, including 71 Black and 62 White women.

The overall mutational burden between Black and White women with TNBC was not significantly different, with a median of 5 somatic changes per patient (point mutations and CNVs combined) for the customized panel (range 1-31 for Blacks vs. 1-26 for Whites; p = 0.76). Of the 151 genes examined, none were mutated at a significantly higher frequency in Black than in White cases, whereas two genes were mutated at a higher frequency in White cases-PIK3CA and NCOR1. No significant difference in the frequency of CNVs was observed between Black and White women with TNBC in our study population.

Of gene mutations and CNVs in TNBC tumors from Black and White women, only PIK3CA and NCOR1 had significantly different, although slight, frequencies by race. These results indicate that overall differences observed in the mutation spectra between Black and White women with breast cancer are likely due to the differential distributions of breast cancer subtypes by race.