Prognostic significance of pretreatment laboratory parameters in combined small-cell lung cancer

Despite the increasing incidence of combined small-cell lung cancer (C-SCLC) in recent years, there have not been many data on clinical prognostic factors predicting prognosis of C-SCLC patients. In present study, we sought pretreatment features especially basic laboratory parameters predicting survival of C-SCLC. We analyzed 613 small-cell lung cancer (SCLC) patients at our institution between January 2005 and December 2010. We identified 114 patients with C-SCLC. The pathologic and clinical characteristics of these patients were reviewed. Data of laboratory parameters obtained during regular examinations at diagnosis of these patients were examined. The Kaplan-Meier method was used to calculate the survival rate and depict the survival curves. The Cox regression model was used to analyze the independent factors affecting the overall survival (OS). These data were compared with the results obtained from our 499 pure SCLC patients who presented during the same time period. Of the 613 SCLC patients analyzed, 18.6 % of the patients presented with C-SCLC. No difference in OS was observed in patients with C-SCLC and patients with pure SCLC (P = 0.995). The Kaplan-Meier survival curves revealed that poor ECOG-PS (P < 0.001), extensive disease (P < 0.001), pathologic subtype of SC/LC (P < 0.001), not receiving surgery (P = 0.001), elevated serum lactate dehydrogenase (LDH) (P = 0.005), elevated NSE (P = 0.043), and elevated neutrophile-lymphocyte ratio (NLR) (P = 0.018) were associated with adverse prognosis of patients with C-SCLC. By multivariate analysis, OS was affected by ECOG-PS (hazard ratio 2.001, P = 0.012), disease extent (hazard ratio 3.406, P < 0.001), and NLR (hazard ratio 1.704, P = 0.030) in C-SCLC patients, while the risk factors that influenced the prognosis of the patients with pure SCLC were ECOG-PS (hazard ratio 2.132, P < 0.001), disease extent (hazard ratio 1.482, P < 0.001), and LDH (hazard ratio 1.811, P < 0.001). Patients with C-SCLC carry a similar prognosis than those with pure small-cell variety. Easily accessible pretreatment parameters such as NLR should be considered in defining the prognosis of C-SCLC patients besides disease extent and performance status.