Cancer cells are characterized by a low antigenic immunogenicity, a rapid growth and an immunosuppressive effect on the extracellular matrix. These properties induce a weak immune response in colorectal cancer (CRC) carcinogenesis. It is therefore crucial to determine the composition of the inflammatory mass, including neutrophils, macrophages and eosinophils in the tumor tissue of patients with CRC, and to analyze other clinicopathological parameters. The present study included 144 patients diagnosed with CRC. Tissue samples obtained from routine histopathological diagnosis were stained with hematoxylin and eosin. Inflammatory cells were assessed in the invasive front and in the center of the tumor by light microscopy under a high-power magnification. The percentage of neutrophils in the invasive front was significantly higher compared with that in the center of the tumor mass (P<0.01). Macrophages and eosinophils were present in the invasive front and in the center of tumor mass in most cases. The presence of neutrophils, macrophages and eosinophils was correlated with various clinicopathological features. Patients with macrophages present in the center of tumor mass had longer disease-free survival time (P=0.041). In conclusion, the present study demonstrated that the inflammatory cell infiltrate served a significant role in the immune response of patients with CRC. It should be noted that the presence of macrophages localized in the stroma of the central part of the primary tumor mass was associated with the survival time of patients with CRC.
Keywords: colorectal cancer; deposits; eosinophils; inflammatory cells; macrophages; neutrophils; prognostic significance.