Endocrine Abstracts

The majority of differentiated thyroid cancer (DTC) cases will be successfully treated with surgery usually (but not always) followed by radioiodine (RAI). The large majority have excellent prognosis. 10% of DTC may present disease progression: local relapse and/or distant metastases. 25–50% of these will slowly loose the capacity to take up radioiodine – RAI refractory cases. Further management includes loco-regional therapies such as surgical excision of lesions causing symptoms, chemoembolization, external irradiation of bone or mediastinal lesions and radiofrequency ablation. When these modalities fail to restrain tumour growth, multi tyrosine kinase inhibitors (TKIs) are used, which are oral antineoplastic agents targeting the molecular pathways activated during tumorigenesis. With these agents a substantial proportion of patients will have at least stabilization of disease. However these agents also have significant side-effects; furthermore, ‘escape’ from their antitumour effect may be observed at follow-up. An interesting agent that may restore the capacity of iodine uptake in the tumour has been reported; relevant clinical trials are now running. Medullary thyroid cancer (MTC) may also present at advanced stage or progress rapidly after surgery. The management of progressive disease includes locoregional therapies as in the case of DTC. Furthermore, agents that target the molecular pathways involved in its pathogenesis - TKIs - have been used. Two of these agents (Vandetanib and Cabozantinib) have been approved in the USA and in Europe for use in MTC patients with progressive disease. These agents are associated with significant increase in the progression free survival. They stabilize disease in the majority of cases. The optimal timing of initiation of such treatments in both types of thyroid cancer has not been clearly defined and should be individualized. The management of these difficult cases requires expertise and a team approach.