Prognostic value of systemic immune-inflammation index in patients with urinary system cancers: a meta-analysis

The systemic immune-inflammation index (SII), an inexpensive and widely available hematologic marker of inflammation, has been linked to tumor progression, metastatic spread, and poor patient prognosis. The objective of this study is to explore the prognostic value of SII in patients with urinary system cancers (USCs).

A comprehensive literature search was conducted by searching the PubMed, EMBASE, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), and Wanfang databases from inception to May 10, 2020, to identify potential studies that assessed the prognostic role of the SII in USCs. The hazard ratio (HR) with a 95% confidence interval (CI) were used to evaluate the correlation between SII and overall survival (OS), progression-free survival (PFS), and cancer-specific survival (CSS) in USCs patients.

A total of 12 studies, including 2,693 USCs patients, were eventually included in the meta-analysis. Elevated SII index was significantly associated with poor OS (HR=1.28, 95% CI: 1.17-1.39, p<0.001), PFS (HR=1.51, 95% CI: 1.25-1.82, p<0.001) and CSS (HR=3.42, 95% CI: 1.49-7.91, p<0.001). Furthermore, subgroup analysis indicated that higher SII than a cutoff value could predict poor OS in renal cell carcinoma (HR=1.23, p<0.001), prostate carcinoma (HR=1.95, p<0.001), bladder carcinoma (HR=5.40, p<0.001), testicular cancer (HR=6.09, p<0.001) and upper tract urothelial carcinoma (HR=2.19, p<0.001). Besides, these associations did not vary significantly by tumor subtypes and stages of USCs, sample sizes, study types, cutoff value defining elevated NLR, treatment methods, and NOS scores.

SII may serve as a useful prognostic indicator in USCs and contribute to prognosis evaluation and treatment strategy formulation. However, more well-designed studies are warranted to verify our findings.