Expression of Bcl-2 but not Bax has a prognostic significance in tongue carcinoma

Among the molecular mechanisms involved in carcinogenesis, defects in the regulation of programmed cell death (apoptosis) make important contributions to the pathogenesis and progression of cancer. Apoptosis regulatory genes include the antiapoptotic bcl-2 gene and the proapoptotic bax gene. The aim of this study was to determine the spectrum of Bax and Bcl-2 expression, and to correlate these findings with clinicopathologic variables and prognosis.

In this study we have evaluated the immunohistochemical expression of Bcl-2 and Bax proteins in a series of 35 squamous cell carcinomas of the tongue.

Immunoreactivity for Bax was detected in 37.1% and for Bcl-2 in 8.6% of cells, and for both proteins the staining was cytoplasmic and granular. Bcl-2 and Bax expression was mainly seen in peripheral cells of epithelial tumor islands with decreasing immunoreactivity toward the center of the neoplastic nests. Bax immunoexpression was significantly correlated with histologic grading (P=0.05), but not with the remaining clinicopathologic variables. Bcl-2 immunoreactivity was significantly correlated with N-stage (P=0.01) and survival. Patients with Bcl-2-negative tumors [mean survival: 73.97 months; 95% confidence interval (CI): 59-88] vs. Bcl-2-positive ones (mean survival: 17.67 months; 95% CI: 6-29) had a longer survival (P=0.01; odds ratio=6.9).

Bcl-2 is associated with aggressive disease, neck lymph node metastasis, and poor prognosis. Whereas Bax is related with histologic grade.