Systemic immune-inflammation index as a prognostic indicator in patients with advanced non–small cell lung cancer receiving first-line chemotherapy combined with immunotherapy

Abstract Background No clear evidence exists regarding the relationship between the systemic immune-inflammation index (SII) and the efficacy of first-line chemotherapy combined with immunotherapy in patients with advanced non–small cell lung cancer (NSCLC). This study aimed to establish the relationship between the SII and survival of patients with advanced NSCLC. Methods This study included 123 patients with advanced NSCLC. The cutoff value of the SII was determined to be 1172 using ROC curve analysis. We evaluated the relationship between the SII and progression-free survival (PFS) and overall survival (OS) using the Cox regression model and Kaplan-Meier (KM) curve analysis. We stratified patients into multiple subgroups based on covariates such as age, sex, and smoking history. Subgroup analysis was used to evaluate the relationship between high SII, disease progression, and mortality risk. Results Univariate analysis indicated that no significant difference existed between SII and PFS, but univariate analysis showed a significant association between SII and OS (hazard ratio [HR] = 1.93, 95% confidence interval [CI] = 1.14–3.29, p = 0.015). The fully adjusted Cox regression analysis also showed a significant correlation between the SII and OS after adjustment for covariables (HR = 1.76, 95% CI =1.02–3.02, p = 0.041). In some subgroups, a high SII positively correlated with the risk of disease progression, and the relationship between a high SII and the risk of mortality was consistent in almost all subgroups. Conclusions These results indicate that pretreatment SII may be an independent predictive marker for patients with advanced NSCLC undergoing first-line chemotherapy combined with immunotherapy. However, large-scale prospective studies are required to confirm our results.