Systemic Immune-Inflammation Index as a Prognostic Marker of Late Recurrence in Operable Gastric Cancer: a Dual-Center Study

Aim: To evaluate the prognostic role of the systemic immune-inflammation index (SII) in patients with operable gastric cancer.

Methods: We assessed 354 patients with operable gastric cancer from tertiary centers in Turkey. SII was calculated by following formula: [neutrophil (cells × 10⁹/L) × platelet (cells × 10⁹/L)]/lymphocyte (cells × 10⁹/L). The best cut-off value for SII was determined by using "receiver operating characteristics (ROC)" analysis. We used log-rank and Cox-regression analysis for survival analyses.

Results: One hundred twenty patients were in the late recurrence group (recurrences have developed 36 months after the surgery). SII was not a prognostic factor in the early recurrence group. However, relapse-free survival (RFS) was longer in SII-low patients than SII-high patients in the late recurrence group. In multivariable analysis, SII was the only independent prognostic factor for RFS in the late recurrence group (hazard ratio (HR): 5.42, 95% CI: 1.18-24.82, p = 0.03).

Conclusion: SII was an independent prognostic factor for RFS in GC patients with late recurrence. Late recurrence risk was higher in SII-high patients than SII-low patients. Inflammation contributes to tumor progression, invasion, and metastasis. Prolonged exposure to chronic inflammation could explain the results of this study.