Biomarker, treatment patterns, and survival differences in metastatic triple-negative breast cancer by race in the United States

Triple-negative breast cancer (TNBC) disproportionately affects Black women, with higher incidence rates and worse outcomes compared with White women. This study included 670 adult patients with metastatic TNBC diagnosed between January 2017 and March 2022 from the Flatiron Clinico-Genomic database. All patients underwent NGS-based testing and were assessed for prevalence of BRCA1/2, PIK3CA, AKT1, and PTEN alterations; treatment patterns; and survival outcomes. Of 670 patients, 28% were Black and 72% White. Black patients had higher BRCA1/2 alteration prevalence (12% vs. 7%; p < 0.04) but similar rates of other mutations. First-line therapy rates were comparable between groups. No significant differences in overall survival were observed (median 13.7 months for Black patients vs. 18.9 months for White patients; p = 0.15). Black patients with metastatic TNBC were nearly twice as likely to have BRCA1/2 alterations, suggesting potential benefit from PARP inhibition. Although survival differences were not statistically significant, larger studies are needed to understand racial disparities in treatments and outcomes.