Thyroid function test abnormalities in patients with metastatic renal cell carcinoma treated with sorafenib

Background: Sorafenib is an orally bioavailable vascular endothelial growth factor receptor (VEGFR) inhibitor with antitumor activity in metastatic renal cell carcinoma (RCC). Sunitinib, also a VEGFR inhibitor, induces biochemical hypothyroidism in 85% of metastatic RCC patients, the majority of whom have signs or symptoms of hypothyroidism. Hence, the incidence of thyroid function test (TFT) abnormalities in patients with metastatic RCC receiving sorafenib was investigated. Patients and methods: Sixty-eight patients with metastatic RCC were treated with sorafenib at the Cleveland Clinic Taussig Cancer Center, and 39 patients had TFTs available. Results: Eight patients (21%) had thyroid dysfunction possibly caused by sorafenib [seven hypothyroidism (18%) and one hyperthyroidism (3%)] and eight additional patients (21%) had findings compatible with nonthyroidal illness. Only two patients had clinical signs and symptoms secondary to thyroid dysfunction and received thyroid hormone replacement. Conclusions: In summary, clinically significant TFT abnormalities were not common in patients treated with sorafenib, and replacement therapy was rarely indicated. TFTs should be measured before sorafenib therapy in RCC patients and subsequently only if clinically indicated.