Hyponatremia in patients with esophageal cancer treated with chemotherapy including cisplatin

Background: Little is known about hyponatremia in patients with esophageal cancer treated with cisplatin-based chemotherapy. The aim of this study was to analyze the risk factors for hyponatremia and its effect on outcomes in patients with esophageal cancer treated with chemotherapy including cisplatin. Methods: We retrospectively analyzed the records of 137 patients with esophageal cancer who received chemotherapy including cisplatin for the first time between January 2011 and December 2014. Results: Hyponatremia (Na < 135 mEq/L) was seen in 77 patients (59%), of whom 29 had Grade 3 (120 ≤ Na < 130 mEq/L) or Grade 4 (Na < 120 mEq/L) hyponatremia. We divided patients into the hyponatremia group (patients with Na < 130 mEq/L) and the control group (patients with Na ≥ 130 mEq/L), and compared the results between the two groups. Three patients (2%) were diagnosed with the syndrome of inappropriate secretion of antidiuretic hormone. The serum sodium level before starting chemotherapy was significantly lower and white blood cell count was significantly higher in the hyponatremia group. Appetite loss was seen significantly more often in the hyponatremia group as the chemotherapy-related adverse effect. There was no significant difference in overall survival between the two groups. Conclusions: Hyponatremia is a common adverse effect induced by cisplatin. Caution should be exercised with patients with a low sodium level before starting chemotherapy. Hyponatremia can be associated with other chemotherapy-related adverse effects, and it should therefore be treated correctly.