Retrospective cohort study of HER2-low expression by race and ethnicity among patients with triple-negative breast cancer

Racial and ethnic disparities in pathologic complete response and overall survival have been reported in patients with triple-negative breast cancer (TNBC). In addition to socioeconomic factors and access to care, differences in tumor biology may affect outcomes. In a cohort study of 31,888 patients with TNBC from the National Cancer Database, Hispanic patients had higher rates of HER2-zero expression (54.0%) than HER2-low expression (46.0%), a significant difference, and higher rates of pathologic complete response to neoadjuvant chemotherapy. No differences were noted among other racial and ethnic groups. In addition, HER2-low expression was associated with lower rates of pathologic complete response. The authors conclude that HER2-low expression and its association with clinical outcomes vary across racial and ethnic groups in patients with TNBC.