Relationships between tumor-associated macrophages and clinicopathological factors in patients with colorectal cancer.

Background: As macrophages have both tumor promoting and inhibiting effects, tumor-associated macrophages (TAM) play a complex role in the regulation of cancer progression and tumor growth. The clinicopathological significance of TAMs in human colorectal cancer remains unclear. Materials and Methods: We investigated the relationships between TAM IF (invasive front), TAM TS (tumor stroma), prognosis and clinicopathological factors in 30 patients with colorectal cancer. Moreover, MVD (microvessel density) was examined for correlation with these factors. TAMs were detected by immunohistochemistry using the anti-CD68 antigen, KP1 mouse monoclonal antibody. MVD was determined by counting the number of CD34-positive vessels. Results: Low TAM IF and TAM TS tended to occur with more advanced colorectal cancer, although this finding was not statistically significant. High TAM IF tended to be found in patients with a good prognosis or those with less recurrence or worsening of their condition. MVD was significantly higher in patients with lymph node metastasis, lymphatic invasion or more advanced tumors than stage III (TNM). Although the correlation between TAM IF, TAM TS and MVD was not statistically significant, the correlation between TAM IF and TAM TS was statistically significant. Conclusion: These results suggest that TAMs may act as one line of defence against malignant cells in patients with colorectal cancer.