Vascular endothelial growth factor (VEGF) plays a crucial role in angiogenesis; it binds to a particular VEGF receptor (VEGFR) to activate the growth, survival and proliferation of vascular endothelial cells. 1,2 Therefore, VEGFR-tyrosine kinase inhibitors (TKIs) are widely used in the treatment of cancers, particularly solid tumours. To date, a total of nine VEGFR-TKIs have been approved for clinical use by the US Food and Drug Administration (FDA) (Table 1). 3 VEGFR-TKIs are used in the treatment of thyroid cancer, because VEGF plays an essential role in the development and progression of thyroid malignancies. 4,5 However, clinical studies have shown that VEGFR-TKIs can induce adverse drug events (ADE), including thyroid dysfunction. [6][7][8] Thyroid dysfunction includes hyperthyroidism and hypothyroidism, both of which could have serious outcomes, and may warrant discontinuation of VEGFR-TKIs treatment. Notably, VEGFR-TKI-induced thyroid dysfunction may be associated with the prognosis of cancer. [9][10][11] The onset of hypothyroidism is usually