The expression of E-cadherin at the invasive tumor front of oral squamous cell carcinoma: immunohistochemical and RT-PCR analysis with clinicopathological correlation.

OBJECTIVE: Pathologists having drawn attention to the morphological and functional characteristics of invasive tumor front (ITF), we attempted to investigate the difference of E-cadherin expression between the ITF and center/superficial part as well as the prognostic value of E-cadherin expression at the ITF. STUDY
DESIGN: We performed a retrospective analysis of the correlation between E-cadherin protein expression at the ITF and center/superficial part and prognostic factors. We also detected the difference of E-cadherin expression at the ITF and center/superficial part using immunohistochemical method, which was further supported in 20 fresh OSCC samples by confocal laser microscopy and RT-PCR methods.
RESULTS: The expression of E-cadherin in the same tumor was heterogeneous. Both protein (t test, P <or= .05) and mRNA (t test, P <or= .05) expression level at the ITF were statistically lower than that of center/superficial part. There was a statistically significant correlation between E-cadherin expression (E-cadherin-negative and E-cadherin-positive group) at the ITF and invasive front grading (IFG) score (P = .026), tumor size (P = .038), and tumor thickness (P = .029). There was a significant difference in 5-year survival between positive (18.18%) and negative (49.59%) expression of E-cadherin at the ITF (P ' .05). Using the Cox regression equation in a stepwise fashion, we found that E-cadherin at the ITF had predictive values in univariate analysis, while it was not an independent predictor of disease-free survival in the multivariate analysis.
CONCLUSIONS: E-cadherin expression at the ITF is lower than that in center/superficial part for most of OSCCs. E-cadherin at the ITF is statistically associated with IFG score, PT and tumor thickness and poor survival of OSCC patients.