Comparison of epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) immunohistochemical expression and outcomes in canine nasal carcinomas treated with radiation therapy

The expression of epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) has been reported in human nasopharyngeal and canine nasal carcinomas. The present study measured EGFR and COX-2 expression and calculated correlations between these proteins and clinical variables and outcomes in dogs with nasal carcinoma treated with radiation therapy. Before treatment, the immunohistochemistry of EGFR and COX-2 was performed in 67 biopsied tissues from canine nasal carcinomas. The correlations between these protein levels, clinical variables, and outcomes were evaluated. EGFR and COX-2 were detected in 88.1% and 82.1% of our samples, respectively. Neither EGFR nor COX-2 was associated with T stage and cribriform plate destruction. Dogs with low EGFR levels had a significantly longer survival time than dogs with high EGFR expression (P=0.043). The COX-2 expression level was not significantly associated with survival times after radiation therapy (P=0.653). Overexpression of EGFR is negatively correlated with survival in dogs with nasal carcinoma. Future studies should identify tumor biomarkers to develop therapeutic targets for effective treatments for canine nasal carcinomas.