EGFR and Ki-67 expression in oral squamous cell carcinoma using tissue microarray technology

Abstract

Our aim was to validate the use of tissue microarrays (TMA) in oral squamous cell carcinomas (OSCC) to analyse epidermal growth factor receptor (EGFR) and Ki-67 expression. We also analysed the relationship that the expression of these markers may have with clinical, pathological and survival variables. The study sample comprised 39 unselected patients diagnosed and treated for OSCC. We analysed Ki-67 and EGFR expression by immunohistochemistry on formalin-fixed, paraffin-embedded surgical specimens. Whole sections (WS) were compared with double 1.5 mm core-tissue microarrays. High EGFR expression was observed both on TMA (in 98% of the cases) and WS (in 100% of the cases) with substantial agreement kappa value (0.720). EGFR expression was not significantly associated with clinical, pathological and survival variables on TMA and WS. Ki-67 analysis showed a Spearman correlation of 0.741 with a Ki-67 mean labelling index of 45% in TMA and 56.8% in WS. We found a significant relationship between gender and Ki-67 labelling index on WS (P = 0.022) and TMA (P = 0.002). Clinical stage was the only parameter in multivariate analysis that had a significant predictive value. We demonstrate that dual 1.5 mm core TMA is a valid, rapid, economical and tissue-saving way to study OSCC biopsies and that it presents strong correlation with the WS. EGFR overexpression in OSCC suggests that these tumours may be a candidate for therapy investigation directed to EGFR.