The role of tumor-associated macrophages in breast carcinoma invasion and metastasis

The main purpose of this study was to investigate the infiltration of tumor-associated macrophages (TAMs) in normal and malignant breast tissue and the draining lymph nodes, and to explore its effect on breast cancer invasion and metastasis. The infiltration densities of TAMs was observed using immunohistochemical staining of CD68 in 100 cases of breast cancer specimens and its paired adjacent non-cancer breast tissues and draining lymph modes, and then to evaluate the relation of TAMs to various clinicopathological features including patients prognosis in breast carcinoma. We observed the infiltration densities of TAMs were significantly higher in breast carcinoma tissue than in adjacent normal tissue and significantly higher in much larger size and higher stage cases. Furthermore, infiltration densities of TAMs have negative correlation with the 5-year survival rates of breast cancer patients. But in matched lymph-nodes, the infiltration densities of TAMs were significantly lower in cancerous metastatic lymph-node samples than in non-metastatic one. Therefore, our data suggests that TAMs infiltration in primary tumor promote invasion and lymphatic metastasis of breast cancer and have negative correlation with patients prognosis in breast cancer, but in lymph-node TAMs may play another role and need further study in the future.