Introduction: Tumor-associated macrophages (TAMs) are recruited into cancer-induced stroma and produce a specific microenvironment for cancer progression. CD204 (+) TAMs are reportedly related to tumor progression and clinical outcome in some tumors. The aim of this study was to clarify the correlation between CD204 (+) TAMs and the clinicopathological features of lung squamous cell carcinoma.
Methods: We investigated the relationships between the numbers of CD204 (+) TAMs and clinicopathological factors, microvessel density, and the numbers of Foxp3 (+) lymphocytes in 208 consecutively resected cases. We also examined the relationships between the numbers of CD204 (+) TAMs and the expression levels of cytokines involved in the migration and differentiation of CD204 (+) TAMs.
Results: A high number of CD204 (+) TAMs in the stroma was significantly correlated with an advanced p-stage, T factor, N factor, and the presence of vascular and pleural invasion. A high number of CD204 (+) TAMs in the stroma was also a significant prognostic factor for all p-stages and p-stage I. Moreover, the numbers of CD204 (+) TAMs were correlated with the microvessel density and the numbers of Foxp3 (+) lymphocytes. A high number of CD204 (+) TAMs was strongly correlated with the tissue expression level of monocyte chemoattractant protein-1. CD204 (+) TAMs were shown to be significant independent prognostic factors in a multivariate analysis.
Conclusions: CD204 (+) TAMs were an independent prognostic factor in lung squamous cell carcinoma. CD204 (+) TAMs, along with other tumor-promoting stromal cells such as regulatory T cells and endothelial cells, may create tumor-promoting microenvironments.