Bcl-2 as a prognostic factor for survival in small-cell lung cancer

The expression of Bcl-2 oncoprotein is associated with inhibition of apoptosis and prolonged cell survival. The purpose of this study was to investigate Bcl-2 protein expression in patients with small-cell lung cancer (SCLC) in order to see if it was related to clinicopathological features and to prognosis.

Forty patients with SCLC were stained immunohistochemically using specific monoclonal antibody (DAKO-Bcl-2, 124). Bcl-2 positivity was determined as detection of the oncoprotein in greater than 10% of neoplastic cells.

Immunopositivity was present in 26 (60%) of SCLC patients. Twenty-three of 40 (57.5%) patients had limited disease at presentation, and 17 of 40 (42.5%) had extensive disease. There was not any correlation with Bcl-2 protein expression and clinicopathological parameters such as sex, age, smoking history and performance status. According to the extent of the disease, Bcl-2 expression was significantly higher in patients with extensive disease (p < 0.009). Bcl-2 expression was associated with significant shorter survival in patients with SCLC (Log Rank = -5.26; p = 0.00001). Cox regression analysis controlling for age, sex and tumor stage, confirmed that Bcl-2 expression (HR = 0.049 p < 0.0001) and N stage (HR = 0.152 p < 0.012) were an independent prognostic markers for poor prognosis. In CONCLUSION Bcl-2 oncoprotein was expressed in most cases of SCLC and its expression may have prognostic importance.