Endocrine Abstracts

Medullary thyroid cancer (MTC) is a rare disease accounting for about 5% of all thyroid cancers and can occur sporadically (75%) or as part of the familial syndrome multiple endocrine neoplasia type 2 (MEN 2). The hereditary forms are caused by a mutation in the ‘rearranged during transfection’ (RET) gene.

When a proven RET mutation is present carriers will be offered a prophylactic thyroidectomy. The timing of this prophylactic procedure is not completely clear for the choice between the risks of the complications of an early thyroidectomy versus the possible risk of disease development when delaying surgery is still difficult.

Most MTC patients present with an asymptomatic palpable solitary thyroid nodule and/or suspicious enlarged cervical lymph nodes. When diagnosed about 50% of the MTC patients show lymph node and 10% already have distant metastases. About 20% will die from progressive metastatic disease. The prognosis depends strongly on disease stage. The 10-year overall survival is 95% in patients with localized disease, and 75 and 40% in patients with respectively regional and metastasized disease

Tumour progression can be predicted by calcitonin and CEA doubling times and also ¹⁸F-FDG-PET and ¹⁸F-DOPA-PET are useful in guiding therapeutic steps in patients with MTC. The treatment for MTC is still a topic of discussion. American guidelines recommend total thyroidectomy, level VI and ipsilateral level II–V lymph node dissection when nodal involvement is suspected, while the British guidelines advocate bilateral selective lymph node dissection in T2–4 tumours or palpable lymph nodes in level VI and II–V. For metastatic disease local treatment options (radiofrequency ablation, radiotherapy) are available. Tyrosinekinase inhibitors show encouraging results, however no benefits on overall survival have yet been demonstrated.Several other different strategies for the treatment of MTC are currently being considered, many of which target downstream proteins of RET.