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

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 ( increment SII) in colorectal cancer (CRC) after curative resection. This study was designed to evaluate the role of increment 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 increment 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 increment 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- increment SII group (>127.7) and 87.6% and 79.8% in the low- increment SII group (<= 127.7). The 3-year and 5-year DFS rates, respectively, were 54.1% and 34.1% in the high- increment SII group and 80.3% and 78.5% in the low- increment SII group. In the univariate analysis, smoking, pathological stages III-IV, high-middle degree of differentiation, lymphatic invasion, vascular invasion, and the high-Delta SII group were associated with poor OS. Adjuvant therapy, pathological stages III-IV, vascular invasion, and Delta SII were able to predict DFS. Multivariate analysis revealed that pathological stages III-IV (HR=0.442, 95% CI=0.236-0.827, p=0.011), vascular invasion (HR=2.182, 95% CI=1.243-3.829, p=0.007), and the high-Delta SII group (HR=4.301, 95% CI=2.517-7.350, p<0.001) were independent predictors for OS. Adjuvant therapy (HR=0.415, 95% CI=0.250-0.687, p=0.001), vascular invasion (HR=3.305, 95% CI=1.944-5.620, p<0.001), and the high-Delta SII group (HR=4.924, 95% CI=2.992-8.102, p<0.001) were significant prognostic factors for DFS. Conclusions. The present study demonstrated that increment SII was associated with the clinical outcome in CRC patients undergoing curative resection, supporting the role of increment SII as a prognostic biomarker.