Expression of the apoptosis suppressing protein bcl-2 in prostatic adenocarcinoma is related to tumor malignancy

BACKGROUND. The expression of bcl-2 protein has been related to histopathological features and prognosis in several epithelial tumors. In prostatic adenocarcinoma the prognostic significance of bcl-2 expression is mainly unexplored. METHODS. The expression of bcl-2 protein was assessed in 235 prostatic adenocarcinomas by using monoclonal bcl-2 protein antibody after microwave pretreatment of the cancer sections. The results of immunohistochemistry were related to histopathological features and prognosis of the patients. RESULTS. 71% of the tumors were bcl-2 negative, in 18% of cases the expression was weak, and in 11% of cases strong. The fraction of bcl-2 positive cells was variable (mean [SE]: 15 [2]%). The expression of bcl-2 protein was positively correlated to high T-category, metastatic disease, and poor histological differentiation of the tumor. Tumors that were aneuploid and rapidly proliferating frequently expressed bcl-2 protein, while tumors we densely infiltrated by inflammatory cells rarely expressed bcl-2. The expression of bcl-2 protein was related to lowered survival probability in univariate analysis, while in multivariate analysis the expression of bcl-2 had no independent prognostic value. CONCLUSIONS. The expression of bcl-2 protein in prostatic adenocarcinoma is related to tumor malignancy, but the prognostic significance of the expression requires further analyses, particularly in localized tumors. (C) 1997 Wiley-Liss, Inc.