The Change of Systemic Immune-Inflammation Index Independently Predicts Survival of Colorectal Cancer Patients after Curative Resection

Abstract

Background. The systemic immune-inflammation index (SII) has an important role in predicting survival in some solid tumors. However, little information is available concerning the change of the SII (∆SII) in colorectal cancer (CRC) after curative resection. This study was designed to evaluate the role of ∆SII in CRC patients who received surgery. Methods. A total 206 patients were enrolled in this study. Clinicopathologic characteristics and survival were assessed. The relationships between overall survival (OS), disease-free survival (DFS), and ∆SII were analyzed with both univariate Kaplan-Meier and multivariate Cox regression methods. Results. Based on the patient data, the receiver operating characteristic (ROC) optimal cutoff value of ∆SII was 127.7 for OS prediction. The 3-year and 5-year OS rates, respectively, were 60.4% and 36.7% in the high-∆SII group (>127.7) and 87.6% and 79.8% in the low-∆SII group (≤127.7). The 3-year and 5-year DFS rates, respectively, were 54.1% and 34.1% in the high-∆SII group and 80.3% and 78.5% in the low-∆SII group. In the univariate analysis, smoking, pathological stages III-IV, high-middle degree of differentiation, lymphatic invasion, vascular invasion, and the high-ΔSII group were associated with poor OS. Adjuvant therapy, pathological stages III-IV, vascular invasion, and ΔSII were able to predict DFS. Multivariate analysis revealed that pathological stages III-IV ( $\text{HR}=0.442$ , 95% $\text{CI}=0.236$ -0.827, $p=0.011$ ), vascular invasion ( $\text{HR}=2.182$ , 95% $\text{CI}=1.243$ -3.829, $p=0.007$ ), and the high-ΔSII group ( $\text{HR}=4.301$ , 95% $\text{CI}=2.517$ -7.350, $p<0.001$ ) were independent predictors for OS. Adjuvant therapy ( $\text{HR}=0.415$ , 95% $\text{CI}=0.250$ -0.687, $p=0.001$ ), vascular invasion ( $\text{HR}=3.305$ , 95% $\text{CI}=1.944$ -5.620, $p<0.001$ ), and the high-ΔSII group ( $\text{HR}=4.924$ , 95% $\text{CI}=2.992$ -8.102, $p<0.001$ ) were significant prognostic factors for DFS. Conclusions. The present study demonstrated that ∆SII was associated with the clinical outcome in CRC patients undergoing curative resection, supporting the role of ∆SII as a prognostic biomarker.