Prediction of Hyponatremia in Patients With Nasopharyngeal Cancer on Concurrent Chemoradiotherapy

Hyponatremia occurs in patients with nasopharyngeal cancer (NPC) on chemoradiotherapy and causes prolonged hospitalization, low quality of life, and increased mortality. This study aimed to determine the associated factors of hyponatremia in patients with NPC on chemoradiotherapy and investigate changes in hyponatremic events over time.

We retrospectively reviewed patients with NPC who underwent complete concurrent chemoradiotherapy between 2014 and 2024. Hyponatremia was defined as serum sodium levels <130 mmol/L. The median follow-up time was reported in person-months (pm); the incidence rate was defined as the number of events per 1000 pm. The Poisson regression model was used to estimate the incident density ratios and identify hyponatremia predictors.

A total of 381 patients were included in this study. The total follow-up time was 59 354 pm; the median follow-up time was 164 pm (interquartile range 135-193). There were 259 patients (68%) who never had hyponatremia. Hyponatremia was common in the first 2 months of treatment. Significant factors shown on univariate and multivariate regression analyses were age >50 years, tube feeding alone, advanced nodal metastasis, distant metastasis, carboplatin use, high-grade mucositis, and skin complications.

Hyponatremia frequently occurs in the first 2 months of NPC treatment. Advanced age, tube feeding alone, advanced nodal metastasis, distant metastasis, carboplatin use, high-grade mucositis, and skin complications are significantly associated with hyponatremic events.