Prognostic significance of Bcl-2 and Bax protein expression in the patients with oral squamous cell carcinoma

The aim of this study was to investigate the expression of the apoptosis-inhibitory Bcl-2 protein and the apoptosis-promoting Bax protein and to identify their association with the clinical parameters and prognosis of the patients with oral squamous cell carcinoma (OSCC). The expression of Bcl-2 and Bax proteins was evaluated by immunohistochemical staining in specimens from 110 patients with OSCC. Every section was scored according to both the percentage of positive staining tumor cells and the staining intensity. The Kaplan-Meier test and Cox proportional hazards regression analysis were performed to assess the correlation between the protein levels and the long survival rate of patients. The association between Bax, Bcl-2 immunoexpression and clinicopathologic variables was analyzed with the chi-square test and non-parametric analysis. The Bcl-2 and Bax immunoexpression in 20 oral mucosa samples were also investigated as normal control. The results showed that the 5-year survival rate was significantly higher in the patients with the ratio of Bcl-2/Bax <= 1 than in those with Bcl-2/Bax > 1 (76.79 +/- 6.69% vs. 59.26 +/- 6.69%, P = 0.0489). Bax immunoreactivity was significantly correlated with histological grading and lymph node metastasis. Univariate analysis indicated that the ratio of Bcl-2/Bax and lymph node metastasis were two independent factors related to the prognosis. The ratio of Bcl-2/Bax could be used as an effective biomarker to predict the prognosis of OSCC.