Analysis of risk factors for cervical lymph node metastases in patients with sporadic medullary thyroid carcinoma

OBJECTIVE: Medullary thyroid carcinoma (MTC) is classified as either sporadic or inherited. This study was performed to analyze the risk factors for cervical lymph node metastases and predict the indication for prophylactic lateral neck dissection in patients with sporadic MTC. METHODS: Sixty-five patients with sporadic MTC were retrospectively reviewed. Univariate analysis with the chi-square test and multiple logistic regression analysis were applied to identify the clinicopathological features (sex, age, tumor size, number of tumor foci, capsule or vascular invasion, and others) associated with cervical lymph node metastases. RESULTS: The metastasis rates in the central and lateral compartments were 46.2% (30/65) and 40.0% (26/65), respectively. The incidence of cervical lymph node metastases was significantly higher in patients with a tumor size of >1 cm, tumor multifocality, and thyroid capsule invasion. Only thyroid capsule invasion was an independent predictive factor for central compartment metastases and lateral neck metastases. The possibility of central compartment metastases was significantly higher when the preoperative serum carcinoembryonic antigen concentration was >30 ng/mL (60.0% vs. 34.3%). CONCLUSIONS: MTC is associated with a high incidence of cervical lymph node metastases. Prophylactic lateral node dissection is necessary in patients with thyroid capsule invasion or a high serum carcinoembryonic antigen concentration.