Medullary thyroid cancer (MTC) is a rare disease and the clinical course of MTC many vary. In this study, we analyzed the factors influencing the prognosis of MTC.

The study group consisted of 37 patients with MTC seen at KNUH between July 1985 and July 2003. We analyzed the medical records of MTC surgical cases in a retrospective study to analyze treatment results and utilized the Kaplan-Meier and chi-squred tests to determine the correlation of prognosis and recurrence.

The median age of patients was 39 years and 7 patients had a family history and accompanying disease. No metastases were detected at the time of diagnosis. The majority of the sizes of tumors were under 4 cm in 22 cases and 24 cases (64.9%) showed unilateral tumor locations. Twenty cases (48.6%) showed lymph node metastasis, and invasion of the surrounding organs was seen in 5 cases (13.5%) of these cases. A total thyroidectomy and central neck dissection was performed in all cases. In 17 cases, a modified radical neck dissection was performed initially. Recurrence was detected in 13 out of 37 cases. The most common site of recurrence was the neck, followed by the lung and liver. We analyzed the factors that affected recurrence and it was found that lymph node metastasis and the TNM stage had a statistically significant relationship. No factor showed relevance to prognosis by multivariate analysis. The survival rates were 89.2% for 5 years and 83.8% for 10 years.

We could not find any statistical significance for a factor relevant to the prognosis of the patients by multivariate analysis. However, as the 10 year-survival rate was 83.8%, we can expect improvement in the treatment of MTC with surgical management (total thyroidectomy and central neck dissection) and constant follow-up.