Impact of low sodium values on survival outcomes of patients with cancer receiving immune checkpoint inhibitors.

Low serum sodium affects cancer prognosis, but its impact on immunotherapy is unclear. Assessing the association of pre- and post-ICI treatment sodium levels with survival. We retrospectively analyzed patients receiving ICI in January 2012-December 2023, collecting serum sodium levels at treatment initiation and 4 weeks post-ICI, with overall survival (OS) as the primary outcome. Low sodium was observed in 125 and 119 patients pre-and post-treatment respectively. Pre-ICI and post-ICI low sodium correlated with decreased OS [10.6 vs. 22.9 months ( = 0.001) and 11.6 vs. 27.2 months ( = 0.009)]. Multivariate analysis identified pre-ICI low sodium [HR: 1.685; 95% CI: 1.050-2.705; = 0.031] as an independent risk factor for worse OS. Low baseline serum sodium was an independent risk factor for poor OS in patients treated with ICIs.