Validity of Weekly Administration of Carboplatin after Carboplatin-Induced SIADH: Two Case Reports and Literature Review

Chemotherapy-induced severe hyponatremia is a life-threatening condition. Platinum-based agents play a key role in ovarian cancer treatment but are more likely to cause hyponatremia than other anticancer agents. The optimal strategy for treating ovarian cancer in cases of severe platinum agent-induced hyponatremia remains unclear. We encountered 2 patients with ovarian cancer who developed syndrome of inappropriate antidiuretic hormone secretion (SIADH) after chemotherapy with involved carboplatin. Case 1 was a recurrent ovarian clear-cell carcinoma with peritoneal dissemination, and the patient developed severe hyponatremia due to SIADH on day 5 after receiving triweekly docetaxel and carboplatin (DC) therapy. The chemotherapy regimen was changed to weekly DC therapy, and she completed six cycles of regimen without electrolyte disturbance or tumor recurrence. Case 2 was a newly diagnosed advanced high-grade serous ovarian carcinoma, stage IIIC, with a BRCA1 mutation. She developed SIADH on day 8 after receiving triweekly paclitaxel and carboplatin (TC) therapy as adjuvant therapy after primary debulking surgery. The regimen was changed to weekly TC therapy, and she completed the schedule of chemotherapy without electrolyte disturbance and transitioned to maintenance therapy with a PARP inhibitor. In conclusion, weekly carboplatin administration might be a promising alternative to triweekly carboplatin administration after the development of carboplatin-induced SIADH.