INTRODUCTIONRadioiodine [RAI]-resistant advanced and progressive differentiated thyroid cancer [DTC], although rare, constitutes a real challenge as its prognosis is poor and available therapeutic options, until now, have been limited. Discovery of a crucial role of distinct tyrosine kinases in DTC pathogenesis opened up new options in systemic treatment. Lenvatinib is an oral potent multi kinase inhibitor [MKI] of different growth factor receptors including VEGFR1/Flt-1, VEGFR2/KDR, VEGFR3, FGFR1,2,3,4, PDGFR-β as well as RET and KIT signaling networks. Its activity against RAI-refractory DTC was demonstrated in clinical studies fulfilling evidence-based medicine [EBM] criteria. The drug showed acceptable tolerance and manageable toxicity.AREAS COVEREDpublished results of phase II and III studies and other reports evaluated the efficacy and safety of lenvatinib in DTC and in medullary thyroid carcinoma.EXPERT OPINIONCurrently there are two different MKIs, lenvatinib and sorafenib, which have demonstrated effectiveness against RAI-refractory DTC. However, to date, the question of which drug should be chosen for first line treatment remains open. The other question: when to start the treatment seems to be no less important. Whether disease progression, even by RECIST, is enough to initiate a therapy or tumor burden also plays an important role? EBM study, to resolve these issues, is our task for the nearest future.