Prognostic nutritional index and prognosis in renal cell carcinoma: A systematic review and meta-analysis

To perform a systematic review and meta-analysis of the Prognostic Nutritional Index (PNI) as a prognostic factor for renal cell carcinoma (RCC).

Eligible studies that evaluated the prognostic impact of pretreatment PNI in RCC patients were identified by comprehensive searching the electronic databases PubMed, Cochrane Central Search library, and EMBASE. The end points were overall/cancer-specific survival (OS/CSS) and recurrence-free/disease-free survival (RFS/DFS). Meta-analysis using random-effects models was performed to calculate hazard ratios (HRs) with 95 % confidence intervals (CIs).

In total, 9 retrospective, observational, case-control studies involving 5,976 patients were included for final analysis. Eight studies evaluated OS/CSS, and 5 evaluated RFS/DFS. Our results showed that lower PNI was significantly associated with unfavorable OS/CSS (HR = 1.68, 95% CI 1.44-1.96, P < 0.001, I² = 9.2%, P = 0.359) and RFS/DFS (HR = 1.98, 95% CI 1.57-2.50, P < 0.001, I² = 18.2%, P = 0.299) in patients with RCC. Subgroup and meta-regression analysis based on ethnicity, study sample size, presence of metastasis, PNI cut-off value, Newcastle-Ottawa quality assessment scale (NOS) score, and gender ratio all showed that lower PNI was associated with poorer OS/CSS and RFS/DFS. Funnel plots and Egger's tests indicated significant publication bias in OS/CSS (P = 0.001), but not in RFS/DFS (P = 0.757).

This meta-analysis indicated that lower PNI was a negative prognostic factor and associated with tumor progression and poorer survival of patients with RCC. Therefore, PNI could be a potential prognostic predictor of treatment outcomes for patients with RCC.