Impact of Serum Sodium Levels on Treatment Efficacy and Prognosis in Advanced Renal Cell Carcinoma Patients Receiving Subsequent Line Nivolumab

Aim: We aimed to evaluate the effect of serum sodium levels on treatment efficacy and prognosis in metastatic renal cell cancer (RCC) patients receiving subsequent line Nivolumab.Methods: This retrospective, single-center study include 55 patients (n=55). Clinicopathological factors and serum sodium levels were recorded before nivolumab (pre-ICI) initiation and at the eighth week of nivolumab (post-ICI). Patients were divided into two groups according to the median sodium levels for pre-ICI (138 mEq/L) and post-ICI 137 (mEq/L). Cox regression analysis was used to determine proportional hazards.Results: The median age of the study population was 63 (33-90) and 44 (78.6%) patients were male. Progression-free survival (PFS) ans overall survial (OS) was similar for pre-ICI sodium low and high patients. However, post-ICI sodium-high patients had significantly longer PFS [30.9 months, 95% CI; (2.0-59.9) ve 3.4 months, %95 CI; (0.0-7.1); respectively (p<0.001)] and OS [NR vs 9.1 months, 95% CI; (0.0-22.6); (p<0.001)] than the patients with low post-ICI sodium levels. In the multivariate analyses, the only independent predictor was post-ICI sodium level for both PFS [HR: 0.288; 95% CI 0.149-0.559, (p<0.001)] and OS [HR: 0.239; 95% CI, 0.107-0.533, (p<0.001)]. Conclusion: Our results are consistent with those of previous studies showing the prognostic and predictive value of serum sodium levels. As serum sodium is an easy, fast, and affordable marker, it may be a feasible prognostic marker. More comprehensive studies are needed to highlight this topic.