[Is RAI for Thyroid Cancer No More Needed?].

Approximately, 5-10% of differentiated thyroid cancer patients experience distant metastases. 131I radioiodine(RAI)therapy fails in 60-70% of them, resulting that patients of less than 5% are categorized in the RAI refractory group including patients of RAI non-avid lesions and those of RAI avid but insufficient lesions. Redifferentiation of RAI accumulation has been examined with a variety of pharmaceuticals such as MKIs and BRAF/MEK inhibitors. Redifferentiation effects are monitored by scintigraphic findings and RAI therapy can be applied again. The phenomenon that patients with RAI avid lesions would not respond to RAI therapy may be explained by insufficient lesional radiation doses. In such cases, shrinkage of lesions with interventional drugs before RAI therapy would result in increase of lesional radiation doses. Such kind of strategy should be incorporated in future patient management.