[Radiometabolic therapy for metastatic thyroid carcinoma: overview of the literature and rational bases for the use of recombinant human TSH].

The established treatment for differentiated thyroid carcinoma (DTC) is founded on total thyroidectomy and subsequent administration of radioiodine (131I) to ablate the thyroid remnant and to treat the metastatic disease. In the case of metastatic or recurrent disease, further cycles of 131I therapy are often necessary. The condition for maximizing the effectiveness of the treatment is to have an adequate stimulation from TSH, which must be >25-30 mIU/L. This elevation is achieved either discontinuing the hormone suppression therapy for an appropriate period, or administering recombinant human TSH (rhTSH). The latter has shown good clinical efficacy in patients with residual thyroid gland and is nowadays commonly employed since it is easy to use and allows to avoid the side effects of hypothyroidism. It thus represents a good alternative to thyroid hormone withdrawal for the remnant ablation, while is still open the question if its efficacy on the management of metastatic disease is superimposable to thyroid hormone withdrawal. To this purpose, a Panel of expert reviewed the literature, assessing the advantages and disadvantages for the patient, as well as the impact in terms of cost and benefit to the National Health Service. The work of the Panel concluded with a proposal for the use of rhTSH in selected patients with metastatic DTC, in which is considered the efficacy and safety of the product and is examined its use in terms of costs; this proposal was accepted by the Italian Drug Agency resulting in an update of the indications for rhTSH.