Tumor-associated macrophages: Harbingers of aggressiveness in oral squamous cell carcinoma

BACKGROUND: The significance of the tumor microenvironment (TME) as a modulator of tumor behavior was acknowledged by Hanahan and Weinberg in 2011 as the emerging hallmarks and enabling characteristics of the hallmarks of cancer. Subsequently, the role of inflammation, in conferring aggressiveness to a tumor, was regarded as a fundamental process in the evolution of the TME. Tumor-associated macrophages (TAMs) are distinctly polarized inflammatory cells and key shapers of a protumorigenic microenvironment. AIMS: The aim of the study was to evaluate the distribution of TAMs and the expression of CD-163 as a marker to evince tumor aggressiveness, in oral squamous cell carcinoma (OSCC). SETTINGS AND DESIGN: A retrospective institutional study was approved by the institutional ethics committee, and random sampling was carried out. Cases fulfilling the inclusion criteria were subjected to S(site), T(tumor), N( node), M( metastasis), P(pathology) STNMP staging along with immunohistochemical evaluation of CD-163. METHODS: Samples for this study included 58 archival cases of OSCC. Demographic details were recorded, and the STNMP stage ascertained, following which, each case was reevaluated histopathologically for the invasive front. Cases with sufficient stroma and demonstrating the invasive front were further subjected to immunohistochemical evaluation of CD-163 for TAMs. The density of CD-163-positive cells was assessed by three pathologists, independently, in a double-blinded evaluation using Image-J©. STATISTICAL ANALYSIS: Descriptive data were evaluated and analyzed statistically using Spearman's/Pearson's correlation tests based on the distribution of data. RESULTS: The density of TAMs was noted to be directly proportional to the STNMP stage. In addition, a strong positive, statistically significant correlation was noted between the density of TAMs and tumor size, nodal status and STNMP stage. CONCLUSION: The crucial role of the tumor microenvironment must be considered when evaluating OSCC. TAMs prove to be a reliable marker for assessing tumor aggressiveness and could aid in improved prognostication of OSCC, while also being potential targets for therapy.