Introduction: To systematically assess the predictive significance of systemic immune-inflammation index (SII) in renal cell carcinoma (RCC).
Methods: Relevant studies published before November 2022 were retrieved from public databases. Hazard ratio (HR), standardised mean difference (SMD) and relative risk (RR) were calculated to estimate associations of SII with prognosis, treatment responses and clinicopathological features.
Results: Twenty studies involving 6887 patients were eligible. The meta-analysis results revealed a high SII level was associated with worse overall survival (HR: 1.45, p < 0.001), progression-free survival (HR: 1.63, p = 0.001), cancer-specific survival (HR: 1.86, p < 0.001), lower overall response rate (RR: 0.62, p = 0.003), disease control rate (RR: 0.69, p = 0.002), larger tumour size (SMD: 0.39, p = 0.001), poorer IMDC risk (RR: 7.09, p < 0.001), higher Fuhrman grade (RR: 1.54, p = 0.004), tumour stage (RR: 1.67, p = 0.045), the presence of distant metastasis (brain: RR, 2.04, p = 0.001; bone: RR, 1.33, p = 0.024) and tumour necrosis (RR: 1.57, p = 0.031). Subgroup analysis showed SII predicted OS and PFS for non-Asian, but CSS for both Asian and non-Asian populations.
Conclusion: Pre-treatment SII may be a promising predictor of clinical outcomes for RCC patients.
Keywords: Renal cell carcinoma; clinicopathological features; meta-analysis; prognosis; systemic immune-inflammation index; treatment.