Tumor-associated Tissue Eosinophilia Predicts Favorable Clinical Outcome in Solid Tumors: A Meta-analysis

Background: Activated eosinophils have been deemed to affect carcinogenesis and tumor progression via various mechanisms in tumor microenvironment. However, the prognostic role of tumor-associated tissue eosinophilia (TATE) in human cancers still remains controversial. Therefore, we performed the meta-analysis to better understand the role of TATE in prognosis prediction for cancer patients. Methods: We searched PubMed and EBSCO to identify the studies evaluating the association of TATE and overall survival (OS) and/or disease-free survival (DFS) in cancer patients, then computed extracted data into hazard ratios (HRs) for OS, DFS and clinicopathological features such as lymph node metastasis etc with STATA 12.0. Results: A total of 6125 patients from 25 published studies were incorporated into this meta-analysis. We found that the presence of TATE significantly improved OS and 5-year DFS in all types of cancers. In stratified analyses based on cancer types, pooled results indicated that eosinophils infiltrating into tumor tissue was significantly associated with better OS in oral cancer, esophageal carcinoma and colorectal cancer. In addition, TATE was significantly inversely correlated with lymph node metastasis, tumor stage and lymphatic invasion of cancer. Conclusion: TATE leads to a favorable clinical outcome in cancer patients, implicating that it is a valuable biomarker for prognostic prediction for human cancers and clinical application of biological response modifiers or agonists promoting TATE may be the novel therapeutic strategy for patients.