Can pre-diagnostic serum levels of sodium and potassium predict prostate cancer survival?

There is evidence that derangement in serum electrolytes like sodium and potassium is associated with increased morbidity and mortality among hospitalized critically ill patients, but their role in the context of cancer survival remains poorly understood. We sought to investigate the association of pre-diagnostic serum sodium and potassium with risk of overall, cancer-specific, and cardiovascular (CV) death among 11,492 men diagnosed with prostate cancer (PCa) from the Swedish AMORIS study. Multivariable Cox proportional hazards regression was used to assess the risk of death by clinical categories of pre-diagnostic serum sodium and potassium. During a mean follow-up of 5.7 years, 1649 men died of PCa. Serum levels of sodium were not indicative of PCa-specific or CV death. A weak positive association was found between pre-diagnostic higher serum potassium (> 5 mEq/L) and overall death [HR: 1.26 (95% CI: 1.01-1.59)] as compared to low/normal levels of clinical cut-offs. The current study did not find strong evidence for a role of electrolytes in PCa mortality. To further disentangle the potential role of electrolytes in cancer development, future studies should use repeated measurement of serum electrolytes. This research project was reviewed and approved by the Stockholm Ethical Committee (Dnr 2010/1:7).