A case of successful tolvaptan treatment for syndrome of inappropriate secretion of antidiuretic hormone that developed during chemotherapy for cervical cancer

Abstract

Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a condition in which excessive antidiuretic hormone secretion accelerates water reabsorption and causes hyponatremia. Possible causes of SIADH include central nervous system disorders, pulmonary disorders, ectopic ADH-producing tumors, and medication. SIADH cases with malignant tumors account for 27.7%of all SIADH cases. We encountered a case of SIADH that developed during chemotherapy for stage IVB cervical cancer where the concomitant use of tolvaptan, a vasopressin V2-receptor antagonist, allowed us to continue chemotherapy, resulting in a partial response. The patient was a 48-year-old woman with a history of two pregnancies and two deliveries. She visited her previous doctor with a chief complaint of irregular genital bleeding and was referred to us with a suspicion of cervical cancer. Cervical histology revealed a diagnosis of endocervical adenocarcinoma, usual type with high-grade neuroendocrine carcinoma. Imaging studies revealed metastases from the pelvis to the para-aortic and mediastinal lymph nodes, liver, lungs, and the fourth cervical vertebra. After starting chemotherapy (Paclitaxel, Cisplatin, and Bevacizumab), hyponatremia with impaired consciousness was observed, and a diagnosis of SIADH was made. Because tolvaptan administration improved hyponatremia, chemotherapy could be continued, and a partial response was obtained. Tolvaptan was effective in treating SIADH that developed during chemotherapy for cervical cancer.