Research Progress on the Prognostic Significance of Systemic Immune Inflammation Index in Patients With Resected Colorectal Cancer: A Meta-Analysis.

[AIM] The systemic immune-inflammation index (SII) serves as a prognostic index of survival among cancer patients. SII is calculated based on the counts of lymphocytes, neutrophils, and platelets. This study aimed to conduct a meta-analysis to explore the predictive role of SII in patients who have undergone surgery for colorectal cancer (CRC).

[METHODS] A comprehensive search of Web of Science, PubMed, the Cochrane Library, and EMBASE databases was performed to include studies published until 12 Dec 2023. The association between SII and overall survival (OS) in CRC patients who had undergone surgery was assessed by hazard ratios (HRs) and 95% confidence intervals (CIs).

[RESULTS] A total of 10 studies with 4537 cases published between 2017 and 2023 were included in this meta-analysis. The mean age of the patients was 60.8 years. The pooled result showed that high SII was correlated with poorer OS (HR = 2.21, 95% CI = 1.95-2.49, p < 0.001) and poorer DFS (HR = 2.81, 95% CI = 2.36-3.34, p < 0.001) in CRC patients who underwent surgery. The cut-off value of SII to predict OS would be 550. Subgroup analysis of SII and survival outcomes in CRC confirmed these findings.

[CONCLUSIONS] SII emerges as a useful tool for prediction of survival outcomes in patients undergoing CRC surgery, especially in the elderly population over 60 years old.