Objective: The expression of epidermal growth factor receptor (EGFR) is one of the indicators, which can predict the malignant potential of squamous cell carcinoma of the head and neck (HNSCC). On the other hand, previous histological studies have proved tumor-associated tissue eosinophilia (TATE) to be a favorable prognostic indicator for HNSCC. We studied the prognostic significance of co-expression of EGFR and TATE. Methods: We examined the expression of EGFR and TATE in 53 patients with nasopharyngeal carcinoma (NPC). Biopsy specimens were subjected to immunohistochemical-staining for EGFR expression and Luna-staining for TATE. EGFR staining was considered negative when immuno-stained cells were less than 25% in a field. TATE was divided into four grades as grade 0 for 0-2 eoshinophils in a high power field, grade 1 for 3-9, grade 2 for 10-29, and grade 3 for 30 or more. Results: In terms of TATE expression, 27 patients were classified as grade 0, 12 as grade 1, six as grade 2, and eight as grade 3. Forty-four patients were EGFR positive and nine were negative. We found no statistical significance in the distribution of EGFR positivity and TATE grades. Among EGFR-positive patients, 5 year survival rates were significantly better in TATE-positive (grades 1, 2, 3) patients than in TATE-negative (grade 0) patients (P=0.0139). Conclusion: Eosinophils may be activated in the tumor tissue, in which the expression of EGFR is up-regulated. This suggests that the activated eosinophils in EGFR-positive tumors resulted in better prognoses. TATE infiltration and EGFR expression may be closely related to the malignant potential of NPC, and co-expression of TATE and EGFR may be an important prognostic factor.
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