p53 and Bcl-2 protein expression and its relationship with prognosis in small-cell lung cancer

Small-cell lung cancer (SCLC) has a poor prognosis despite good initial response to chemotherapy. Therefore, it is important to identify molecular markers that might influence survival and serve as potential therapeutic targets. Previous studies have demonstrated immunohistochemical expression of p53 and Bcl-2 in approximately 40%-90% and 55%-90% of patients with SCLC, respectively, but its relationship with prognosis remains controversial. To determine the correlation between the expression of p53 and Bcl-2 and disease-free survival, age (< 70 vs. >or= 70 years), sex, clinical stage (limited vs. extensive), performance status (World Health Organization stages 0-4), and weight loss (10% of body weight), we retrospectively studied 58 SCLC parafin sections of transbronchial biopsy specimens immunostained using monoclonal antibody against N-terminus of the human p53 protein and monoclonal antibody against Bcl-2 oncoprotein. p53 and Bcl-2 expression were observed in 41% and 57% of patients, respectively. p53 and Bcl-2 expression were not correlated with disease-free survival. There was also no correlation of p53 and Bcl-2 expression with age, sex, weight loss, and performance status. There was a significant correlation of p53 (P < 0.001) and Bcl-2 (P < 0.045) expressions with limited-stage disease.