New Insights Into the Role of Tissue Eosinophils in the Progression of Colorectal Cancer: A Literature Review.

INTRODUCTION

Amongst the inflammatory cells implicated in the immune surveillance of colorectal cancer, a growing body of evidence suggests a role for eosinophils in carcinogenesis. We aimed to review the value of tumour-associated tissue eosinophilia (TATE) in the prognosis of colorectal cancer emphasizing the identification and measurement of tissue-infiltrating eosinophils and their association with the clinicopathological features of the disease.

MATERIAL AND METHODS

We used PubMed and Web of Science search engines to retrieve studies that looked at the association between tissue eosinophils and colorectal cancer prognosis.

RESULTS

We selected 15 studies for our review. In the majority of the studies, eosinophils were identified in hematoxylin-eosin stained sections and scores were generated for analysis. Most of the studies pointed to tumour-associated tissue eosinophilia as a favourable prognostic marker in colorectal cancer and found an inverse association between eosinophil count and the metastatic potential of these neoplasms. The association between tumour-associated tissue eosinophilia and established prognostic markers of colorectal cancer was assessed in some studies, with inconsistent results. Additionally, tumour-associated tissue eosinophilia decreased with the adenoma-carcinoma progression of colorectal lesions.

DISCUSSION

Several mechanisms have been proposed regarding eosinophil chemoatraction to tumour tissues and eosinophil-cancer cell cross-talk, suggesting that eosinophils are actively involved in colorectal cancer progression. Although a scoring system is still lacking, tumour-associated tissue eosinophilia meets the criteria of a convenient histopathological prognosticator in colorectal cancer.

CONCLUSION

Collectively, current evidence associates the presence of eosinophils in the colorectal cancer microenvironment with the modulation of tumour progression. The clinical impact of this finding deserves future research.