RET and metastatic neoplasm: Two tyrosine-kinase inhibitors (TKIs) are currently used as a first-line treatment of symptomatic MTC with unresectable, locally advanced or metastatic disease: cabozantinib, a potent inhibitor of RET, vascular endothelial growth factor receptor (VEGFR)-2 and c-Met [10,11,12]; and vandetanib, targeting RET, VEGFR-2/3 and epidermal growth factor receptor (EGFR) [13,14].