Phosphorylated EGFR at tyrosine 1173 correlates with poor prognosis in oral squamous cell carcinomas

Abstract

To evaluate the expression of epidermal growth factor receptor (EGFR) and phosphorylated EGFR (pEGFR), in oral squamous cell carcinomas (OSCC). We examined their utility as prognostic markers by relating to clinicopathological characteristics and the clinical outcome. We analysed 74 primary OSCC and examined immunohistochemical expression of EGFR and pEGFR (phosphorylated at tyrosine 1173) using tissue microarray technology. Their role in survival was assessed by Kaplan-Meier method and Cox regression models. Epidermal growth factor receptor expression was observed in all cases, and pEGFR expression was observed in 41.1% of the cases. We found a significant correlation between EGFR and pEGFR expression (P=0.003). In the multivariable analysis for cause-specific survival, we found an independent prognostic value for pEGFR expression (HR 7.94, 95% CI 2.03-31.06, P=0.003) and for clinical stage (HR 2.88, 95% CI 1.10-7.53, P=0.031). For recurrence-free survival, clinical stage (HR 6.59, 95% CI 1.36-31.90, P=0.019) and tumour grade (HR 3.35, 95% CI 1.07-10.44, P=0.037) presented independent prognostic value. Epidermal growth factor receptor is highly expressed in OSCC and is phosphorylated in more than one-third of the cases. The independent value of pEGFR expression in cause-specific survival of OSCC suggests that this marker may serve as reliable biological marker to identify high-risk subgroups and to guide therapy.