Tumor-associated macrophages (TAMs): clinical-pathological parameters in squamous cell carcinomas of the lower lip

The objective of this study was to analyze the presence of tumor-associated macrophage (TAM) subpopulations M1 and M2 in squamous cell carcinoma of the lower lip (SCCLL) by immunohistochemitry, and to evaluate the possible role of these subtypes in the development of regional lymph node metastasis and their association with clinical and pathological parameters. Forty-two cases of SCCLL were divided into two groups (21 with and 21 without regional lymph node metastasis). The histopathological grade of malignancy was determined and the material was submitted to double staining with anti-CD68/anti-CD163 and anti-CD68/anti-HLA-DR monoclonal antibodies. The results were analyzed statistically using the Wilcoxon signed-rank and Spearman correlation tests. The M1 and M2 subpopulations were observed in all cases studied. No significant difference was observed between the quantities of M1 and M2 TAMs regarding tumor size (p > 0.05). A significantly larger number of M2 compared to M1 TAMs was observed in tumors without regional lymph node metastasis, tumors in early stages, and low-grade tumors (p < 0.05). No significant difference between the numbers of M1 and M2 TAMs was observed in tumors with regional lymph node metastasis, tumors in advanced stages, and high-grade tumors (p > 0.05). There was a positive weak correlation between M1 and M2 TAMs (r = 0.361; p = 0.019). The results suggest a more important role of M2 TAMs in early stages than advanced stages of lip carcinogenesis. The progression of SCCLL does not seem to be related to an imbalance of macrophage polarization in the microenvironment of these tumors.