Pro-gastrin-releasing peptide and neuron-specific enolase: useful predictors of response to chemotherapy and survival in patients with small cell lung cancer

The aim of this study was (1) to evaluate and predict the value of ProGRP and NSE in therapy and survival; (2) as well as to investigate the correlation between the ProGRP mRNA expression in peripheral blood and serum ProGRP protein. The study included 122 patients with SCLC without prior therapy. The serum levels of ProGRP and NSE were detected by enzyme-linked immunosorbent assay and eletro-chemiluminescence immunoassay, respectively. The expression of ProGRP mRNA was detected by real-time reverse transcriptase-polymerase chain reaction. Distribution of serum levels of ProGRP, NSE and ProGRP mRNA differed significantly according to tumor size, disease stage and distant metastasis (all P < 0.05), and no association was found between them and gender or age (both P > 0.05). After two courses of chemotherapy, patients of remission and stable groups showed a marked decrease in ProGRP and NSE concentrations (P < 0.05). The ProGRP concentration of patients in progression group was significantly higher than pretreatment level (P < 0.05), while NSE concentration was not. A linear nonparametric (Spearman) correlation test revealed that there was a significant correlation between ProGRP mRNA expression in peripheral blood and serum ProGRP protein level (P < 0.05). Univariate analysis found a statistically significant association of survival with disease stage, distant metastasis, ProGRP and NSE (P < 0.05). Gender, age and tumor size were not prognostic factors (P > 0.05). Multiple Cox regression model analysis found that only disease stage and NSE were significant predictors (P < 0.05). This study has found that there is a potential role for ProGRP and NSE in both therapy monitoring and predicting survival in SCLC patients.