An immunohistochemical evaluation of tumor-associated macrophages (M1 and M2) in carcinoma prostate - An institutional study.

Background: Tumor-associated macrophages (TAM) are the main component of inflammation along with leukocytes, endothelial cells and fibroblasts together form a tumor microenvironment, with immune cells representing its vital component. Many studies suggested that TAMs cumulating in tumors correlate with a poor prognosis. In prostate cancer, TAMs can increase cancer cell invasion by stimulating tumor angiogenesis, degrading the extracellular matrix, and also suppresses the antitumor functions of cytotoxic T cells resulting in poor prognosis.

Aims and objectives: : 1. To determine the expression of M1 (CD68) and M2 (CD163) in prostate carcinoma (Pca). 2. To find the association between M1, M2 macrophage with Gleason's score and stage of Pca.

Materials and methods: : This is a retrospective observational study. All transurethral resection prostatic (TURP) chips positive for Pca and the clinical details were collected. Radiologic findings with respect to stage of disease, size of lesion, were noted.

Results: Among the 62 cases studied, majority of the cases were in-between the age of 61-70 years. Highest cases were seen in Gleason's score 8, 9, and 10 (62%), prostatic specific antigen (PSA) levels 20-80 ng/mL (64%), tumor size 3-6 cm (51.6%), T3 stage (40.3%), N1 lymph node stage (70.9%). M1 stage of (31%). CD68 and CD163 expression was analyzed with Gleason's score, TNM stage and PSA levels. CD68 score 3 correlated with low distant and nodal metastasis 6.2% and 6.8%, respectively. CD163 score 3 correlated with high metastasis to lymph nodes and distant metastasis of 86.3% and 25%, respectively. On further analysis, statistically convincing association between the CD163 expression and Gleason's score, PSA levels, nodal and distant metastasis was found.

Conclusion: CD68 expression was correlated with good prognosis with less nodal and distant metastasis and Cd163 expression has poor outcome with increased chances of nodal and distant metastasis. Further exploration of TAM mechanisms and immune checkpoints in the prostate tumor microenvironment can furnish new light and motives for the treatment of Pca.