Effect of preoperative systemic immune inflammation index on the prognosis of postoperative gastric cancer patients

Objective To study the relationship between preoperative systemic immune inflammatory index (SII) and the prognosis of postoperative patients. Methods A retrospective analysis was made on 1 509 patients with gastric cancer who underwent gastric cancer surgery at the Department of Gastrointestinal Surgery, Affiliated Tumor Hospital of Harbin Medical University from Jan 1991 to Dec 2012. The SII values [SII = (platelets x neutrophils) / lymphocytes] were calculated and grouped according to the SII mean. The relationship between SII and clinical factors was analyzed. Results Preoperative mean SII was 570.5, substratified into SII 570.5 group (638 cases). There was a statistically significant difference between SII level and gender(χ2= 4.239, P= 0.040), tumor maximum diameter(χ2= 31.852, P< 0.001), total serum protein(χ2= 7.962, P= 0.005), Alb/Glob ratio(χ2=26.127, P< 0.001) and Hb(χ2= 64.647, P< 0.001). The 1-, 3-, and 5-year survival rates were 77.1%, 42.4%, 31.4% and 68.9%, 28.1%, 19.8%, respectively(χ2= 39.557, P< 0.001). Multivariate analysis showed that tumor TNM stage(HR= 1.592, 95%CI: 1.401-1.809, P<0.001), infiltration depth(HR= 1.256, 95%CI: 1.145-1.377, P< 0.001), lymph node metastasis(HR= 1.177, 95%CI: 1.042-1.329, P= 0.009), tumor maximum diameter(HR= 1.151, 95%CI: 1.006-1.317, P= 0.040), Hb(HR= 0.832, 95%CI: 0.737-0.940, P= 0.003)and SII(HR= 1.337, 95%CI: 1.187-1.505, P< 0.001)were independent risk factors for the prognosis of patients with gastric cancer. Conclusions SII is an independent risk factor for the prognosis of patients with gastric cancer. Preoperative SII>570.5 indicates poor prognosis. Key words: Stomach neoplasms; Blood cell count; Prognosis