Prognostic impact of systemic immune inflammation index (SII) in gastric cancer treated with curative intent surgery - a systematic review and meta-analysis

Abstract

Background: Several blood cell parameters have been identified to have a prognostic impact on patients with resected gastric cancer (GC). The systemic immune inflammation index (SII) is an objective biomarker that reflects the balance between host inflammatory and immune response status. This systematic review investigated the prognostic role of the pretreatment SII in GC patients undergoing surgery with a curative intent. Methods: A systematic literature search for studies investigating the prognostic role of SII in GC in MEDLINE (via PubMed) and Web of Science was performed. We performed meta-analysis of the hazard ratios (HRs) related to survival throughout the study period, and of relative risks concerning 5-year overall survival (OS). Results: In the systematic review, ten studies and a total of 7611 patients were included. A total of seven studies, comprising 3724 patients, were included in the meta-analysis. The pooled analysis indicated that a high pretreatment SII predicted poor survival (HR=1.80, 95% CI=1.45-2.25, p<0.001, I2=64%, p<0.01) in GC treated with curative surgery. Consistently, 5-year OS was lower in high SII groups (RR=0.79, 95% CI=0.70-0.90, p<0.001, I2=67%, p=0.03). Discussion: A high pretreatment SII significantly associated with poorer survival outcomes in CG patients submitted to R0 resection. These results suggest that SII may have the potential to be a prognosis predictive marker with important clinical utility. However, more multicentric, prospective studies assessing larger samples are needed to confirm these findings.