Apoptosis-associated markers and clinical outcome in human oral squamous cell carcinomas

Background: Apoptosis is a genetically regulated cell death involved in the deletion of cells in normal or malignant tissues. Proteins of the Bcl-2 family play a key role in the control of apoptosis and carry out both pro-apoptotic and anti-apoptotic functions. The present study evaluated the prognostic value of Bcl-2 and Bax expression at the invasive front of oral squamous cell carcinoma (OSCC), taking clinicopathological findings into account. Methods: Fifty-six specimens of OSCC were randomly selected, and Bcl-2 and Bax expression was evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded pre-treated specimens at the invasive front of OSCC. Clinicopathological data were gathered and patient survival was analysed. Results: No significant relationship was found between Bcl-2 or Bax expression and clinical variables. Patients with Bcl-2 expression had a worse prognosis than those without Bcl-2 expression, but the difference did not reach statistical significance. Patients with Bax expression had a significantly better prognosis than those without Bax expression (P < 0.05). In univariate analyses, T category, mode of cancer invasion and Bax expression showed significant correlations. Multivariate analysis revealed that the mode of cancer invasion and Bax expression were significant and independent variables. Bax expression was found to be the strongest independent prognostic parameter. Patients with negative Bcl-2 expression and positive Bax expression had a significantly better prognosis (P < 0.005). Conclusions: We suggest that Bax expression at the invasive front of OSCC is a significant predictor of prognosis and that it is therefore important to investigate the expression of Bcl-2 and Bax in this disease.