Prognostic significance of tumor-associated macrophages in breast cancer: a meta-analysis of the literature

PURPOSE: Tumor associated macrophages (TAMs) are important prognostic factors and have been proved to be associated with the invasion and migration of various cancer. However, the relationship between TAMs and breast cancer outcomes remains unclear. EXPERIMENTAL DESIGN: Sixteen studies with a total of 4,541 breast cancer patients were included in this meta-analysis. Correlation of TAMs with overall survival (OS), disease-free survival(DFS), relapse-free survival (RFS), breast cancer special survival (BCSS) and clinicopathological features were analyzed. Survival data and clinicopathological value were integrated by analyzing hazard ratio(HR) and odds ratio(OR) separately and using Fixed-effect or Random-effect model according to heterogeneity. All statistical tests were two-sided. RESULTS: OS and DFS were correlated with high density of TAMs with HR= 1.504(1.200, 1.884)/ 2.228(1.716, 2.892) respectively. And subgroup analysis of location and biomarker in OS and DFS group showed prognosis was associated with TAMs distribution and biomarker selection. Besides, TAMs high infiltration was significantly related to age, size, histologic grade, ER/PR status, basal phenotype and vascular invasion. CONCLUSION: High density of TAMs was associated with poor survival rates of breast cancer. TAMs in stroma are associated with worse outcome than that in nest and using CD68 as a biomarker for TAMs to evaluate the risk is better than CD163 or CD206 alone. Moreover, high infiltration of TAMs was significantly associated with negative hormone receptor status and malignant phenotype. TAMs infiltration can serve as a novel prognostic factor in breast cancer patients.