Prognostic significance of hyponatremia induced by systemic chemotherapy in a hospital-based propensity score-matched analysis

概要

Background:
Today, the growing high incidence of cancer is an important problem in developed countries. In Japan, the Japan Cancer Surveillance Research Group has reported that the probability of developing cancer over the lifetime is 62% in men and 46% in women. The standard treatment for patients at an inoperative stage is systemic chemotherapy mainly for the purpose of extending overall survival (OS), however, accurate and satisfactory specific parameters for predicting prognosis have not been established. In addition, adverse events induced by anticancer drugs often occur, causing deterioration of the patient’s quality of life (QOL). Among the adverse events, electrolyte abnormalities are common and manifest regardless of the primary cancer site, and hyponatremia induced by chemotherapy (HIC) is one of the most frequently encountered adverse events in clinical practice This study aimed to investigate the prognostic impact of HIC using a propensity matching method in cumulative pooled data.

Methods
Between January 2011 and July 2017, 2129 patients were administered systemic chemotherapy for malignancy in various organs at Nagoya City University Hospital. Patients were divided into two groups: a grade 0–1 group (control group) and a grade 3–4 group (severe group) according to the severity of HIC appearing within 30 days after starting treatment. Kaplan–Meier curves were used for survival and recurrence analyses using a propensity case-matched analysis.

Result
The number of severe HIC patients was 93 (4.4%). In platinum-containing regimens, HIC appeared at higher frequencies. In the 21.2 months median follow-up period, the median OS (mOS) in the severe group was 49.1 months, which was significantly worse than the mOS in the control group; the OS in the control group did not reach the median. Univariate and multivariate analyses of associated factors in patients with grade 3–4 HIC revealed that renal dysfunction, cisplatin-containing regimen, and infusion of more than 5000 mL fluid was associated with HIC.

Conclusion
This study suggests that severe HIC in the first treatment cycle affects survival time. Chemotherapy patients receiving extensive hydration should be required to undergo frequent monitoring of serum sodium levels, especially patients receiving platinum-containing regimens.