Preoperative systemic immune-inflammation index predicts prognosis of patients with non-metastatic renal cell carcinoma: a propensity score-matched analysis

BACKGROUND: A novel systemic immune-inflammation index (SII), based on the neutrophils, lymphocytes and platelet counts, is associated with the prognosis of several cancers. The present study evaluates the prognostic significance of SII in non-metastatic renal cell carcinoma (RCC). METHOD: The present study retrospectively reviewed the medical record of patients with non-metastatic RCC who underwent nephrectomy between 2010 and 2013. Receiver operating characteristic (ROC) curve analysis was performed to identify the optimal cut-off value. In addition, the propensity score matching (PSM) was performed with a matching ratio of 1:1. Univariate and multivariate Cox proportional hazards models were used to identify the prognostic factors. The results were reported by hazard ratio (HR) with 95% confidence interval (95% CI). RESULTS: A total of 646 patients were included in the final analysis. High SII group (> 529) was significantly associated with older age (P = 0.014), larger tumor (P < 0.001), higher pathological T stage (P < 0.001), higher tumor grade (P < 0.001) and more tumor necrosis (P < 0.001). Multivariate Cox regression analysis demonstrated that the higher preoperative SII was significantly associated with worse overall survival (OS) (HR = 2.26; 95% CI 1.44–3.54; P < 0.001) and cancer-specific survival (CSS) (HR = 2.17; 95% CI 1.33–3.55; P = 0.002). After PSM, elevated preoperative SII was an independent predictor of poor OS (HR = 1.78; 95% CI 1.1–2.87; P = 0.018) and CSS (HR = 1.8; 95% CI 1.07–3.03; P = 0.027). CONCLUSION: In conclusion, preoperative SII is associated with adverse factors for RCC. Furthermore, higher preoperative SII is an independent predictor of poor OS and CSS in surgically treated patients with non-metastatic RCC. More prospective and large scale studies are warranted to validate our findings.