Elevated neutrophil-lymphocyte ratio combined with hyponatremia indicate poor prognosis in renal cell carcinoma

Background: Elevated neutrophil-lymphocyte ratio (NLR) and hyponatremia each predict poor prognosis in renal cell carcinoma (RCC). Since no previous studies have looked at the combined effect of these two prognostic markers, we examined how NLR and hyponatremia combined associates with mortality and hypothesized that elevated NLR and hyponatremia at RCC diagnosis and at RCC recurrence indicate poorer prognosis.Material and methods: Using Danish medical registries 1999-2015, we included 970 patients from two regions with incident RCC and a measurement of NLR and sodium. NLR was categorized as ≤3.0 and >3.0 and sodium as < lower limit of normal (LLN) and ≥ LLN. Outcomes were survival after RCC diagnosis and first recurrence, respectively. We estimated absolute survival and hazard ratios (HR) using multivariate Cox regression.Results: At RCC diagnosis, 559 (57.6%) had NLR >3.0 and 240 (24.7%) had hyponatremia, the 5 year-survival rate was 35.2% in NLR > 3.0 vs. 69.2% in NLR ≤3.0, adjusted HR 1.8 (95% confidence intervals (CI), 1.4; 2.2). In patients with NLR >3.0 and concomitant hyponatremia vs. NLR ≤3.0 and normal sodium the 5-year survival rate was 21.7% vs. 73.2%, adjusted HR 2.8 (95% CI, 2.1; 3.8). At RCC recurrence, patients with NLR >3.0 and hyponatremia similarly had poorest survival, adjusted HR 3.6 (95% CI, 1.0; 12.8).Conclusion: Elevated NLR alone and in combination with hyponatremia at time of initial RCC diagnosis and at time of RCC recurrence are associated with poor prognosis. Combining these two prognostic markers yield a stronger association than NLR considered alone. This may impact prognostic prediction and its related therapeutic strategy.