bcl-2 oncoprotein in surgically resected nonsmall cell lung cancer: Possibly favorable prognostic factor in association with low incidence of distant metastasis

BACKGROUND: The bcl-2 oncoprotein serves a regulatory function in permitting several cell types to die in an apoptotic process. Its overexpression probably plays a role in tumorigenesis and tumor development. The aim of this study was to determine the clinicopathological and prognostic significance of the bcl-2 oncoprotein in patients with nonsmall cell lung cancer (NSCLC). METHODS: Immunostaining for bcl-2 oncoprotein was performed on 182 operable NSCLCs. RESULTS: Thirty-six patients (19.8%) showed a positive immunostaining for bcl-2 oncoprotein. Histologically, its incidence was higher in squamous cell carcinomas (29.6%). Its expression status was inversely correlated with tumor development-associated parameters such as tumor stage in NSCLCs, especially in squamous cell carcinomas, bcl-2 positive patients with NSCLCs, especially squamous cell carcinomas, showed better overall survival and disease-free survival (DFS). In a multivariate analysis, this oncoprotein status had prognostic value in DFS for NSCLCs and in overall survival for squamous cell carcinomas. The recurrence of bcl-2 positive NSCLCs was significantly uncommon in distant extrathoracic organs. CONCLUSIONS: The expression of bcl-2 oncoprotein in NSCLCs may be an early event of tumor development, especially in squamous cell carcinomas, and may be of importance in determining tumor progression and prognosis.