Correlation Between SII and Lymphocyte Subsets in Gastric Cancer Patients and Its Prognostic Importance.

[PURPOSE] This study aims to investigate the correlation and clinical significance of the systemic immune-inflammation index (SII), which reflects the inflammatory state, with lymphocyte subsets representing the immune system.

[METHODS] The clinical-pathological and laboratory data of 95 patients with gastric cancer and 44 healthy controls were retrospectively analyzed in this study. The relationship between SII and clinicopathological characteristics, lymphocyte subsets, and other indicators was assessed through the Chi-square test and Spearman correlation analysis. Kaplan-Meier curves, log-rank test, and Cox regression were used for survival analysis.

[RESULTS] Compared with the control group, gastric cancer patients have higher SII (p < 0.01) and lower CD3 T cell (p = 0.001), CD4 T cell (p = 0.004), CD8 T cell (p = 0.003), and B cell absolute counts (p < 0.01). Among them, SII has the highest diagnostic value for gastric cancer (AUC = 0.850, p < 0.01) and is positively correlated with TNM staging (p < 0.01). SII shows a significant negative correlation with the absolute counts of CD4 T cells (r = -0.320, p = 0.002). Gastric cancer patients with high SII (p = 0.003) and low CD4 T cell (p = 0.007), B cell (p = 0.001), and NK cell counts (p = 0.001) had shorter survival times. SII (HR = 3.304, p = 0.036) was independent risk factors influencing the prognosis of patients with gastric cancer.

[CONCLUSION] SII in gastric cancer patients exhibits the strongest correlation with CD4 T cells among lymphocyte subsets, and an elevated SII is an independent risk factor for poor prognosis.