Tumor-associated tissue eosinophilia in human esophageal squamous cell carcinoma

Background: Inflammatory cell infiltration around the sites of carcinoma invasion is believed to play important roles in carcinoma biological behavior. Materials and Methods: The status of inflammatory cell infiltration at the sites of frank invasion in 97 cases of esophageal squamous cell carcinoma (SCC) were examined, with special emphasis on the status of tumor-associated tissue eosinophilia (TATE). Infiltration of the CD4+T-cells, CD8+T-cells, CD68+macrophages, L26+B-cells, mast cells and eosinophils was quantitatively evaluated in histological tissue sections. The results were then statistically correlated with clinicopathological factors. Results: Among tumor-associated inflammatory cells, the number of tumor-associated eosinophils was significantly correlated with the presence or absence of vascular invasion, lymph node (LN) metastasis and recurrence. The cases were tentatively classified into 2 categories, small and large groups, according to the median and/or average number of tissue eosinophils. The survival curve of the patients was evaluated according to this classification. No statistically significant differences were detected between these 2 groups in the cases without LN metastasis. However, the large group was associated with a statistically significant better prognosis in cases associated with LN metastasis, especially in those with invasion to adventitia (T3) of the esophagus. Conclusion: The possible function of tumor-associated eosinophils has not yet been elucidated, but these findings indicate the importance of TATE in the biological behavior of SCC of the esophagus.