Prognostic value of neuroendocrine markers for predicting survival in patients with small cell lung cancer

Patients with small cell lung carcinoma (SCLC) present neuroendocrine (NE) properties and chromogranin A (CGA), synaptophysin (Syn), and neural cell adhesion molecule 1 (NCAM1) are known as NE diagnostic markers, while the predictive value of the NE differentiation in SCLC remains uncertain. The aim of this retrospective study was to evaluate the prognostic significance of NE markers in tissue level in SCLC. A total of 192 patients were enrolled in the study, 136 (70.8%) patients received chemotherapy, and 10 (5.2%) patients were underwent lobectomy resection. The expression levels of the NE markers were performed using immunohistochemistry (IHC). Our data showed the positive expression rates of CGA, Syn, and NCAM1 were 112 (58.3%), 160 (83.3%), 166 (86.5%), respectively. There were significant associations between CGA, NE markers and disease stage, lymph node metastasis in SCLC (P<0.05). A multivariate analysis was performed using Cox regression model, the results showed that disease stage (P<0.001), regional lymph node metastasis (P<0.001), CGA expression (P=0.019), NE differentiation (P=0.033), chemotherapy (P=0.001), and surgery (P=0.001) were independent factors associated with overall survival. Kaplan-Meier and log-rank test demonstrated that patients with low expression of CGA (Log rank P=0.015) and low level of NE markers (Log rank P=0.028) proved to have significant longer survival compared to those with the opposite status of each variable. In conclusion, low CGA level or low NE markers by IHC in SCLC are both prognostic determinants. Further studies are needed to elucidate the function of particular SCLC subtype in cell lines.