MEDULLARY
THYROID CANCER – A PARTICULAR HISTOLOGICAL SUBPTYPE OF THYROID CANCER WITH AN
AGGRESSIVE BIOLOGICAL BEHAVIOR
Medullary
thyroid cancer (MTC) was described by Jacquet (over 100 years ago) in the
German literature, as a ‘malignant goiter with amyloid’ and named by Hazard et
al in 1959. MTC originates from the neural crest derived parafollicular C-cells
of the thyroid gland. These cells secrete the polypeptide calcitonin (Ctn) and
the carcinoembryonic antigen (CEA). Intravenously administered calcium, pentagastrin,
or both together are potent Ctn secretagogues. MTC may occur either
sporadically (in the majority of cases, 75 %) or in an hereditary basis (~ 25
%) (component of Multiple Endocrine Neoplasia type 2 [MEN 2A or MEN2B] or of
familial MTC [FMTC]). MTC is a more aggressive endocrine malignancy compared to
the more common differentiated (papillary and follicular) thyroid cancer (5-year
survival 83 % vs. 95 % for MTC and differentiated thyroid cancer, respectively).
Cervical lymph node metastases are commonly observed in patients with MTC (70 –
80 %). The presence of distant metastases significantly aggravates prognosis
(10-yrs survival 95 % vs. 40 % for patients with MTC confined to the thyroid
gland vs. patients with distant metastases, respectively). Radical surgery remains the cornerstone in the treatment of
MTC. Since radioactive iodine is not absorbed by C-cells, radioiodine
ablation therapy is not effective in the management of MTC.
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