SII (HR = 3.304, p = 0.036) was independent risk factors influencing the prognosis of patients with gastric cancer.<h4>Conclusion</h4>SII in gastric cancer patients exhibits the strongest correlation with CD4<sup>+</sup> T cells among lymphocyte subsets, and an elevated SII is an independent risk factor for poor prognosis. The gene discussed is CD4; the disease is gastric cancer.