Expression of bcl-2 protein is associated with shorter survival in nonsmall cell lung carcinoma

The aim of this study was to assess the relationship between the expression of the 27-kilodalton (kD) bcl-2 protein and survival among nonsmall cell lung carcinoma (NSCLC) patients.

Paired tissue samples of histologically confirmed tumor and uninvolved lung of 91 randomly selected NSCLC patients were used in this study. The expression of 27-kD bcl-2 proteins in uninvolved lung and tumor tissue specimens was analyzed using Western blot analysis. Overall survival was estimated using the Kaplan-Meier method. The relation between patient survival and expression of the 27-kD bcl-2 protein in uninvolved lung, tumor, and in uninvolved lung and/or tumor tissue specimens was assessed using log-rank tests and Cox proportional hazards multiple regression.

The 27-kD bcl-2 protein was expressed in 54% of the uninvolved lung tissue specimens, in 53% of the tumor tissue specimens, and in 70% of the uninvolved lung and/or tumor tissue specimens. When NSCLC patient survival was considered with respect to the expression of the 27-kD bcl-2 protein, a statistically significant shorter survival was observed for patients whose tissue samples expressed the 27-kD bcl-2 protein in the uninvolved lung and in the uninvolved lung and/or tumor (log-rank test, P = 0.008 and P = 0.001, respectively). Cox proportional hazards multiple regression models also showed statistically significant associations between shorter survival and positive 27-kD protein expression in the uninvolved lung (hazard ratio of 2.27; P = 0.05) and in the uninvolved lung and/or tumor (hazard ratio of 5.58, P = 0.008) after controlling for tumor size, stage, the type of surgery received, smoking status, age, and cell type.

In the current study, patients with nonsmall cell lung carcinoma with positive expression of the 27-kD protein bcl-2, either in the uninvolved lung or in uninvolved lung and/or tumor, were found to have significantly poorer postresection survival.