Prognostic evaluation of the expression of p53 and bcl-2 oncoproteins in patients with surgically resected non-small cell lung cancer

Background: Tumor staging remains the most important prognostic predictor in patients with non-small cell lung cancer (NSCLC). However, the prognostic significance of expression of oncoproteins involved in regulation of cellular uncontrolled proliferation remains controversial. Methods: In this retrospective study, we investigated the expression of bcl-2 and p53 oncoproteins in 114 surgically resected NSCLC patients (46 stage I, 39 stage II and 29 stage IIIa) using immunohistochemical analysis and correlated the molecular markers with survival. Results: Positive bcl-2 immunoreactivity was detected in 26 of 114 (22.8%) NSCLC, including 15 of 43 (34.9%) squamous cell carcinoma and 11 of 71 (15.5%) adenocarcinoma cases. Nuclear staining for p53 was observed in 59 of 114 (51.8%) NSCLC, including 26 of 43 (60.5%) squamous cell carcinoma and 33 of 71 (46.5%) adenocarcinoma patients. There was no correlation between pathological staging and expression of bcl-2 and p53. However, the expression frequency of bcl-2 was significantly higher in squamous cell carcinoma than in adenocarcinoma (P < 0.02). The presence of bcl-2 expression did not provide a favorable prognosis (P = 0.23) and the overexpression of p53 oncoprotein was also not significantly associated with adverse prognosis (P = 0.09). No inverse relationship was found between bcl-2 and p53 expression (P = 0.83). Conclusion: Expressions of bcl-2 and p53 using immunohistochemical staining are not independent prognostic predictors in patients undergoing surgery for NSCLC.