Objective:To analyze the expression of CECR2 and the distribution of M2 macrophages in prostate cancer tissues,and to explore the relationship between the expression of CECR2 and the distribution of M2 macrophages in the progression of prostate cancer.Methods:Clinical and tissue specimen data of 98 inpatients who underwent prostate cancer surgery were collected.The expressions of cat-eye syndrome chromosome region candidate gene 2(CECR2)and CD163 antibody in prostate cancer tissues were detected by immunohis-tochemical staining,and the relationship between their expressions and clinicopathological features was analyzed.Results:CECR2 was highly expressed in benign prostate tissues,with a positive rate of 87.76％,while it was lowly expressed in prostate cancer tissues,with a positive rate of 28.57％.The positive rate of CECR2 in prostate cancer tissues was lower than that in adjacent benign prostate tissues(P＜0.05).The low expression of CECR2 in prostate cancer tissues was closely related to the presence of nerve invasion,extraprostatic spread,intraductal carcinoma,tumor grade and T stage(P＜0.05).The median number of CD163-positive macrophages(M2 macropha-ges)in prostate cancer tissues was 21.03 per high-power field,while that in adjacent benign prostate tissues was 4.23 per high-power field.The infiltration density of CD163-positive macrophages in cancer tissues was higher than that in adjacent benign prostate tissues.Further analysis of the relationship between the expression of CECR2 and the distribution of M2 macrophages showed that 47 of the 70 ca-ses with low expression of CECR2 had high-density distribution of M2 macrophages(CD163 positive),and the low expression of CECR2 was positively correlated with high-density distribution of M2 macrophages.Conclusion:There is a significant downregulation of CECR2 expression in prostate cancer tissues,and its low expression is related to the infiltration density of M2 macrophages.CECR2 may induce M2 macrophage polarization,regulate the tumor immune microenvironment,and thereby promote the progression of prostate cancer.