Systemic Immune-inflammation Index Predicts Survival of Patients After Curative Resection for Non-small Cell Lung Cancer

Background: The systemic immune-inflammation index (SII) is reported to be associated with clinical outcomes and has been proven to be a promising prognostic indicator in several solid tumor types. To the best of our knowledge, however, no studies regarding SII in patients with resectable non-small cell lung cancer (NSCLC) are available. Materials and Methods: Three hundred forty-one patients with NSCLC who underwent surgery at our Institution between 2008 and 2012 were included. The SII was calculated using the formula: platelet count x neutrophil/lymphocyte count. The optimal cutoff value was calculated using the Cutoff Finder (http://molpath. charite. de/cutoff). Univariate and multivariate analyses were calculated by the Cox proportional hazards regression model. Results: The optimal cut-off value was 471.2x109/l for SII. A low SII was associated with female gender, never smoking status, adenocarcinoma histology, higher pathological TNM stage and low level of serum C-reactive protein, but not age, serum carcinoembryonic antigen or cytokeratin 19 fragment level. Patients of the low SII group had a significantly better 5-year overall survival than those with high SII (83.61% vs. 60.39%, p< 0.001). Multivariate analysis revealed that the SII was a significant independent predictive indicator for cancer-specific survival (p = 0.007). Conclusion: This is the first study to demonstrate that the SII could represent an independent prognostic factor for patients with resectable NSCLC.