Prognostic Value of Systemic Immune Inflammation Index in Squamous Cell Lung Cancer

Abstract

Background/Objectives: Squamous cell lung cancer (SCC) presents a significant treatment challenge due to its poor prognosis and limited therapeutic options. In many resource-limited countries, access to advanced molecular testing is often unavailable, making the identification of novel and reliable prognostic markers crucial for improving patient selection for systemic treatments. Methods: This single-center, retrospective study investigated the prognostic value of inflammatory biomarkers, including the systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR), in 134 patients diagnosed with SCC. Patients were stratified into groups based on optimal cut-off values determined by ROC analysis for each biomarker. Results: Elevated levels of the SII, NLR, and PLR were significantly associated with shorter overall survival in patients with SCC (all p < 0.05). Conclusions: These easily accessible and cost-effective laboratory parameters are particularly valuable in settings where molecular testing is not available, aiding in the identification of high-risk patients and optimizing treatment selection for chemotherapy.

Keywords: neutrophil-to-lymphocyte ratio; overall survival; platelet-to-lymphocyte ratio; squamous cell lung cancer; systemic immune-inflammation index.

Figure 1

TheROC curves for (A) SII (B) NLR, and (C) PLR in lung SCC patients. The solid blue line represents the ROC curve, while the dashed blue lines indicate the confidence intervals. The red diagonal line represents the reference line (chance level). The sensitivity and specificity values at the optimal cutoff point are marked within each graph. (A) The AUC for the SII is 0.690 and the cut-off value is 641.03, with a sensitivity of 0.716 and specificity of 0.700; (B) the AUC for NLR is 0.674 and the cut-off value is 2.564, with a sensitivity of 0.638 and specificity of 0.700; (C) the AUC for PLR is 0.553, and the cut-off value is 165.45, with a sensitivity of 0.643 and specificity of 0.700. PLR: platelet-to-lymphocyte ratio, NLR: neutrophil-to-lymphocyte ratio, SII: systemic immune-inflammation index, ROC: receiver operating characteristics, AUC: area under the curve.

Figure 2

Correlation between the variables: (A) SII and NLR (r = 0.899), (B) SII and PLR (r = 0.648), and (C) NLR and PLR (r = 0.577). The solid red line represents the least squares regression line, while the dashed red lines indicate the 95% confidence interval of the regression. PLR: platelet-to-lymphocyte ratio, NLR: neutrophil-to-lymphocyte ratio, SII: systemic immune-inflammation index.

Figure 3

Kaplan–Meier survival curves for patients stratified by NLR, PLR, and SII scores. (A) NLR score. Patients with a NLR = 1 (<2.564) are represented by the blue curve, and the red curve represents those with a NLR = 2 (>2.564) (log rank test p < 0.0001). (B) PLR score. Patients with a PLR = 1 (<165.45) are represented by the blue curve, and the red curve represents those with a PLR = 2 (>165.45) (log-rank test p = 0.002). (C) SII score. Patients with a SII = 1 (<631.03) are represented by the blue curve, and the red curve represents those with a SII = 2 (>641.03) (log-rank test p = 0.00044). PLR: platelet-to-lymphocyte ratio, NLR: neutrophil-to-lymphocyte ratio, SII: systemic immune-inflammation index.