Correlation of tumor-associated macrophage density and proportion of M2 subtypes with the pathological stage of colorectal cancer.

Abstract

Colorectal cancer (CRC) is a prevalent global malignancy with complex prognostic factors. Tumor-associated macrophages (TAMs) have shown paradoxical associations with CRC survival, particularly concerning the M2 subset. We aimed to establish a simplified protocol for quantifying M2-like TAMs and explore their correlation with clinicopathological factors. A cross-sectional study included histopathological assessment of paraffin-embedded tissue blocks obtained from 43 CRC patients. Using CD68 and CD163 immunohistochemistry, we quantified TAMs in tumor stroma and front, focusing on M2 proportion. Demographic, histopathological, and clinical parameters were collected. TAM density was significantly higher at the tumor front, with the M2 proportion three times greater in both zones. The tumor front had a higher M2 proportion, which correlated significantly with advanced tumor stage (P = 0.04), pathological nodal involvement (P = 0.04), and lymphovascular invasion (LVI, P = 0.01). However, no significant association was found between the M2 proportion in the tumor stroma and clinicopathological factors. Our study introduces a simplified protocol for quantifying M2-like TAMs in CRC tissue samples. We demonstrated a significant correlation between an increased M2 proportion at the tumor front and advanced tumor stage, nodal involvement, and LVI. This suggests that M2-like TAMs might serve as potential indicators of disease progression in CRC, warranting further investigation and potential clinical application.