Medullary thyroid carcinoma (MTC) is an uncommon thyroid tumor. Calcitonin (CT) is a very specific marker of this cancer and has a major place in the postoperative follow-up. The aim of this study was to evaluate the outcome of surgical treatment for MTC and to identify the prognostic factors for the normalization of CT after surgery.

Retrospective analysis of 29 patients with MTC from 1994 to 2002 in Samsung Medical Center was carried out.

22 female and 7 male were identified and their mean age was 46.9 years. Mean follow-up was 42.7 months. 5 patients had MEN2a; all had pheochromocytoma and 2 among them had hyperplasia of parathyroid gland. The majority of patients (86.2%) presented with a palpable neck mass and 23 patients were diagnosed with MTC preoperatively. Total thyroidectomy with or without neck dissection was performed in all patients. Cervical lymph node involvement was detected in 34.5% of these patients. Basal CT levels were found to be normal in 15 patients (51.7%) postoperatively. 1 distant metastasis, 6 loco-regional metastases and 1 death were observed during follow-up period. Overall survival rate was 94.7% and disease-free survival rate was 62.9% at 5 years. Univariate analysis showed that extra-thyroidal invasion and involvement of lymph node were significant prognostic factors for normalization of CT after surgery.

Considering the high recurrence rate in the thyroid bed and cervical lymph node, more extensive and thorough neck dissection is needed for the treatment of MTC.