Differences in Expression of EGFR, Ki67 and p-EPK in Oral Cavity Squamous Cell Carcinoma

Purpose: To evaluate the expression of EGFR, Ki67, and p-EPK in oral cavity and oropharyngeal cancers, and to investigate their clinical significance as prognostic markers.
Methods: One hundred patients who underwent curative surgery for oral cavity or oropharyngeal squamous cell carcinoma in a Chinese People’s Liberation Army General Hospital between March 1999 and October 2010 were evaluated. The level of protein expression of EGFR, Ki67 and p-EPK was assessed by immunohistochemistry. In situ hybridization was used to detect the existence of human papillomavirus (HPV).
Results: Nineteen of 75 patients with oropharyngeal cancer showed HPV-positive tumors, and two of 72 patients with oral cavity cancer showed HPV-positive tumors. EGFR and Ki67 expression was significantly higher in oral cavity cancers than in oropharyngeal cancers (p = 0.005 and p = 0.001, respectively). Loss of p-EPK occurred significantly more frequently in oral cavity cancers than in oropharyngeal cancers (p = 0.004). Overexpression of EGFR and Ki67 and loss of p-EPK were observed more frequently in HPV-negative tumors. Multivariate Cox regression analysis showed that Ki67 expression had a significantly unfavorable impact on relapse-free survival in oropharyngeal cancer.
Conclusion: The expression levels of EGFR, Ki67, and p-EPK differ between oropharyngeal and oral cavity cancer and it may be attributed to HPV-related molecular pathogenesis. The expression of Ki67 might be an unfavorable prognostic marker for relapse-free survival in oropharyngeal cancer.

Keywords
EGFR; Ki67; p-EPK; Oral cavity squamous cell carcinoma; Expression difference