The preoperative systemic immune-inflammation index is associated with an unfavorable prognosis for patients undergoing curative resection of esophageal squamous cell carcinoma after neoadjuvant therapy

Purposes Systemic inflammation and immune status play a critical role in the development and progression of cancers. We evaluated the clinical significance of the preoperative systemic immune-inflammation index (SII) for predicting the long-term outcomes of patients who received neoadjuvant therapy for esophageal squamous cell carcinoma (ESCC). Methods The subjects of this study were 277 patients who underwent curative resection of ESCC after neoadjuvant therapy. The SII was calculated as follows: SII = neutrophil × platelet/lymphocyte counts. Patients were stratified into high and low preoperative SII groups according to the cut-off value calculated by a receiver operating characteristic curve analysis. The Kaplan–Meier method and Cox proportional regression analysis were used to evaluate the correlation of SII to prognosis. Results The optimal cutoff of the preoperative SII was set at 700. Patients were categorized into preoperative SII-low ( n = 203) and SII-high ( n = 74) groups. The preoperative SII was significantly associated with tumor size. The relapse-free survival of patients in the SII-high group was significantly shorter ( P = 0.0087) and preoperative SII-high was identified as an independent prognostic factor (hazard ratio [HR] 1.55, 95% confidence interval [CI] 1.06–2.28, P = 0.0229). The prevalence of hematogenous recurrence was significantly higher in the SII-high group. When we stratified patients into three groups with an additional cutoff value of 1200, we observed an incremental decrease in relapse-free survival rates. Conclusions High preoperative SII was associated with shorter relapse-free survival times for ESCC patients who underwent curative resection after neoadjuvant therapy.