Association of Hyponatremia With Survival in Patients With Castration-resistant Prostate Cancer: A Clinical Commentary

Hyponatremia has been associated with an increased risk of demise in several malignancies. The aim of the current study was to evaluate its prognostic value in patients with castration-resistant prostate cancer. In 186 patients planned for docetaxel chemotherapy, we detected an association between hyponatremia and decreased survival (P = .04). We suggest conducting further well-designed studies including full workup of hyponatremia. Introduction: The aim of this study was to evaluate the prognostic value of hyponatremia in patients with castration-resistant prostate cancer (CRPC) undergoing docetaxel chemotherapy. Patients and Methods: We retrospectively assessed 186 patients who received docetaxel chemotherapy in addition to androgen deprivation for CRPC between 2005 and 2015. We stratified the patients according to their pre-chemotherapy serum sodium level. Hyponatremia was defined as sodium < 135 mmol/L. A Cox proportional regression model was used to estimate overall survival (OS). Results: The median sodium level was 139 mmol/L (interquartile range, 137-141 mmol/L). Hyponatremia was detected in 13 (6.9%) patients. One-half of the patients died during the studied period. The presence of hyponatremia was associated with a decreased probability of OS (hazard ratio, 2.5; 95% confidence interval, 1.0-6.3; P = .04) in univariate analysis. These findings could not be confirmed in the multivariable OS model (P = .21). Conclusion: We observed an association between hyponatremia and worse survival outcomes in our patients with CRPC undergoing docetaxel chemotherapy. However, further well-designed studies with full workup of hyponatremia are needed to validate these findings and to identify the underlying causes for this association in patients with CRPC.