Immunohistochemical detection of neuroendocrine differentiation in non-small-cell lung cancer and its clinical implications

Purpose: The purpose of this study was to prospectively assess the clinical implications of neuroendocrine (NE) differentiation in non-small-cell lung cancer (NSCLC) tumors. Methods: This study accrued subjects suspected to have lung cancer who underwent diagnostic bronchoscopy. Bronchoscopically-biopsied specimens were subjected to routine pathologic examination, and immunohistochemical studies were then performed if lung cancer was diagnosed. Chromogranin-A, synaptophysin, neural cell adhesion molecule, and Leu7 were used to demonstrate NE differentiation. Results: A total of 280 subjects were accrued to this study over a period of 2 years. Among them, 149 subjects were assessable for this study, and 130 were diagnosed as having NSCLC tumors (55 adenocarcinomas, 50 squamous cell carcinomas, 24 NSCLCs not otherwise specified, and 1 typical carcinoid). Large cell NE carcinoma was not observed in this study. Immunohistochemically, NE differentiation was detected in 16% of NSCLC tumors excluding typical carcinoid. By status of NE differentiation of NSCLC tumors, progression-free survivals were similar in 73 patients undergoing non-surgical treatment (positive, n = 10; negative, n = 63) and 43 patients undergoing surgical resection (positive, n = 8; negative, n = 35), respectively. Overall survival of patients with NE-positive tumors appeared to be favorable both for those undergoing non-surgical treatment and those undergoing surgical resection, though the differences in survival were not significant (P = 0.11 and 0.35, respectively). Conclusions: NE differentiation was detected in 16% of NSCLC tumors in our study. However, the prognostic implications of the presence of this feature could not be clearly determined in this study.