Efficacy and safety of tolvaptan for refractory fluid collection and edema in the terminal cancer patients

OBJECTIVE: Tolvaptan, a vasopressin V(2) receptor antagonist, is an oral diuretic. Patients with terminal cancer develop marked fluid retention, and oral diuretics other than tolvaptan have been used as treatments without clear therapeutic effects. Herein, we aimed to study the efficacy and safety of tolvaptan in patients with terminal cancer. METHODS: Tolvaptan was administered at a dose of 7.5 mg/day to 29 patients (median, 72 years) between August 2017 and February 2020. The duration of tolvaptan treatment ranged from 1 to 85 days (mean, 18.5 days). RESULTS: Median albumin (Alb) and transthyretin (TTR) levels on admission were 2.3 g/dL (1.2–4.2 g/dL) and 8.9 mg/dL (2.1–38.2 g/dL), respectively. Median Alb and TTR levels 1 month after treatment initiation remained at 2.3 g/dL (0.8–2.9 g/dL) and 8.6 mg/dL (0.8–23.7 mg/dL), respectively. Regarding renal function indicators, median blood urea nitrogen (BUN) and creatinine levels on admission were 19.9 mg/dL (8.6–49.3 mg/dL) and 0.81 mg/dL (0.38–2.25 mg/dL), respectively. Median BUN and creatinine levels 1 month after treatment initiation were 23.4 mg/dL (13.5–34.0 mg/dL) and 0.91 mg/dL (0.39–2.41 mg/dL), respectively. No patients had hypernatremia on admission, and no effects of tolvaptan on the blood sodium level were found 1 month after treatment initiation. The median potassium level on admission was 4.2 mEq/dL (2.9–5.0 mEq/dL); tolvaptan treatment had no effects on blood potassium level. CONCLUSIONS: Tolvaptan is effective and safe for treating fluid retention refractory to conventional diuretics in patients with terminal cancer.