Prognostic value of pretreatment systemic immune-inflammation index in Chinese esophageal squamous cell carcinoma patients receiving radical radiotherapy: A meta-analysis

Background: The association between pretreatment systemic immune-inflammation index (SII) and long-term survival among Chinese esophageal squamous cell carcinoma (ESCC) patients who received radical radiotherapy remains unclear. The aim of this study was to identify the prognostic role of pretreatment SII in Chinese ESCC patients receiving radical radiotherapy based on current evidence. Methods: The PubMed, EMBASE, Web of Science and CNKI databases were searched up to March 18, 2023. Primary and secondary outcomes were overall survival (OS) and progression-free survival (PFS), respectively. The hazard ratios (HRs) with corresponding 95% confidence intervals (CIs) were combined to assess the predictive role of pretreatment SII for long-term survival of Chinese ESCC patients receiving radiotherapy. All statistical analyses were conducted by STATA 15.0 software. Results: A total of 8 eligibility studies involving 2101 cases were included in this meta-analysis. The pooled results demonstrated that elevated pretreatment SII was significantly related to worse OS (HR = 1.59, 95% CI: 1.24-2.02, P < .001) and PFS (HR = 1.33, 95% CI: 1.13-1.57, P < .001). Besides, subgroup based on TNM stage showed similar results. Conclusion: Pretreatment SII could serve as a novel prognostic factor in Chinese ESCC patients receiving definitive radiotherapy and patients with an elevated SII may experience poorer survival.