Medullary thyroid carcinoma: including MEN 2A and MEN 2B syndromes.

Medullary thyroid carcinoma (MTC) is a rare malignancy with several distinctive features that distinguish its management from other thyroid cancers. First, MTC may be sporadic (75% of cases), or may occur as a manifestation of the hereditary syndrome Multiple Endocrine Neoplasia type 2 (MEN 2) (25% of cases). Additionally, while MTC is more difficult to cure than differentiated thyroid cancer and has higher rates of recurrence and mortality, it is usually a slow growing tumor compared with other malignancies. Finally, unlike differentiated thyroid cancer, there is no known effective systemic therapy for MTC. MTC cells do not concentrate radioactive iodine, and MTC does not respond well to external beam radiation or conventional cytotoxic chemotherapy. These distinguishing features should be considered in planning surgical management of MTC. (c) 2005 Wiley-Liss, Inc.