Medullary thyroid carcinoma.

Medullary thyroid carcinoma (MTC) is subdivided into sporadic (75 %) and hereditary (25 %) forms. Several germline mutations in the RET proto-oncogene are the source of distinct clinical phenotypes in hereditary MTC including familial MTC (FMTC) and multiple endocrine neoplasia 2A (MEN 2A) and 2B (MEN 2B). The higher the penetrance of the MEN 2 phenotype the earlier the progression of MTC which forms the basis for the currently recommended codon-related concept of prophylactic thyroidectomy. In patients with sporadic MTC, routine calcitonin (CT) measurement in nodular goiter patients has been shown to reduce the frequency of advanced tumor stages. Patients with CT levels over 100 pg/ml after pentagastrin stimulation are recommended for total thyroidectomy. In patients with unexpected sporadic MTC after histological examination, completion thyroidectomy is currently only recommended when CT levels remain elevated. The extent of lymph node dissection in patients with MTC is controversial. However, with respect to lymphonodal micrometastases, systematic compartment-oriented microdissection has been shown to reduce the frequency of lymphonodal recurrence. On the other hand, to avoid unnecessary lymph node dissection, a more individualized concept is required in the future. New chemotherapeutic agents (tyrosine kinase inhibitors), therapeutic nuclids (90Yttrium-labeled octreotide), and chemoembolization of liver metastases are currently the most promising therapeutical concepts in patients with distant metastases.