TKIs in MTC patients with progressive disease are associated with a moderate therapeutic benefit, including disease stability or partial responses in up to 73% of cases, decreasing the 10-year disease-specific mortality rate from 38 to 13.5%, mainly seen in patients harbouring RET M918T mutations (Dvorakova et al. 2008, Taccaliti et al. 2011, Kuo et al. 2018). This evidence concerns the gene RET and medullary thyroid gland carcinoma.