Prognostic role of tumour-associated macrophages and macrophage scavenger receptor 1 in prostate cancer: a systematic review and meta-analysis

Recent studies suggested that the tumour associated macrophages may be associated with prostate cancer outcome. A meta-analysis was performed to evaluate the prognostic value of tumor associated macrophages and macrophage scavenger receptor 1, marker for a subset of macrophages, by pooled hazard ratio and 95% confidence intervals from qualified studies following a systemic search. The results indicate that higher infiltration of tumor associated macrophages predicts poor overall survival (HR=1.57, 95%CI: 1.15-1.98), but not biochemical recurrence (HR=1.01, 95%CI: 0.98-1.04) or recurrence-free survival (HR=1.03, 95%CI: 0.05-2.01). In contrast, elevated level of macrophage scavenger receptor 1 was significantly associated with better recurrence-free survival (HR=3.26, 95%CI: 1.22-5.29). Thus, our analysis confirmed the prognostic value of these markers in prostate cancer outcome. We also discussed potential causes of the controversies in the literature and future research directions.