CD68- and CD163-positive tumor-associated macrophages in triple negative cancer of the breast

Tumor-associated macrophages (TAMs) have recently been reported as an important factor in tumor growth and the progression of cancer. The prognostic significance of localizations and densities of TAMs in triple negative cancer (TNC) of the breast is not well understood. The aim of this study was to assess the localizations and densities of the TAMs subtype in TNC and examine their clinicopathological features. The study was based on 107 TNC cases operated on at Dokkyo Medical University Hospital using the pan-macrophage marker CD68 and the M2 macrophage marker CD163 in the tumor stroma (TS) and tumor nest (TN), respectively, and examined the clinicopathological significance. Multivariate Cox regression analyses revealed that age and CD163+ TAMs in both the TS and TN were independent prognostic factors for relapse-free survival and overall survival. No correlation was found between the number of CD68+ cells or the CD163/CD68 ratio either in TS or TN, or clinicopathological features. Our study found that infiltration of CD163+ TAMs, rather than CD68+, in both TS and TN was associated with poor prognosis in TNC patients by multivariate analysis. This suggests that CD163+ TAMs may affect the prognosis of TNC by not only regulating the immune reaction by TAMs in TS, but also because of their direct influence on TN.