Elevated PCNA+ tumor-associated macrophages in breast cancer are associated with early recurrence and non-Caucasian ethnicity

African American and Hispanic women develop more triple negative breast cancer at younger ages than Caucasian women. The frequently observed association between race and socioeconomic status (SES) has confounded our understanding of the outcomes disparities seen in these groups. Given the association between inflammatory cells and high-grade, triple negative tumors, we sought to investigate whether differences in the presence of these cells varies by race. We evaluated breast tumor specimens for the presence PCNA+ tumor-associated macrophages (TAMs) in consecutive cases from a county hospital serving primarily un- or under-insured patients. All patients in this cohort had elevated PCNA + TAM levels. Higher PCNA + TAM counts were associated with hormone receptor (HR) negative tumors and non-Caucasian ethnicity. Hispanic women specifically had significantly higher PCNA + TAM counts than Caucasian patients and shorter disease-free survival. These findings implicate immune function in the development of aggressive breast cancer and suggest a possible link between SES and the inflammatory response.