Risk Factors for Lateral Lymph Node Metastases in Patients With Sporadic Medullary Thyroid Carcinoma

Abstract

Purpose: Medullary thyroid carcinoma is a rare endocrine malignancy; 75% of patients with this disease have sporadic medullary thyroid carcinoma. While surgery is the only curative treatment, the benefit of prophylactic lateral neck dissection is unclear. This study aimed to analyze the clinicopathological risk factors associated with lateral lymph node metastases and determine the indication for prophylactic lateral neck dissection in patients with sporadic medullary thyroid carcinoma.

Methods: The medical records of patients with medullary thyroid carcinoma who were treated at our hospital between January 2002 and January 2020 were retrospectively reviewed; a database of their demographic characteristics, test results, and pathological information was constructed. The relationship between lateral lymph node metastases and clinicopathologic sporadic medullary thyroid carcinoma features were analyzed using univariate and multivariate analyses.

Results: Overall, 125 patients with sporadic medullary thyroid carcinoma were included; 47.2% and 39.2% had confirmed central and lateral lymph node metastases, respectively. Univariate and multivariate analyses identified 2 independent factors associated with lateral lymph node metastases: positive central lymph node metastases (odds ratio = 9.764, 95% confidence interval: 2.610-36.523; p = 0.001) and positive lateral lymph nodes on ultrasonography (odds ratio = 101.747, 95% confidence interval: 14.666-705.869; p < 0.001).

Conclusion: Medullary thyroid carcinoma is a rare endocrine malignancy. Lymph node metastases are common in patients with sporadic medullary thyroid carcinoma. Prophylactic lateral neck dissection is recommended for patients who exhibit positive central lymph node metastases and/or positive lateral lymph nodes on ultrasonography.

Keywords: central lymph node; lateral lymph node; metastases; risk factor; sporadic medullary thyroid carcinoma.

Figure 1.

Flow diagram of the selection process of patients included in this study. Forty-two patients had undergone primary surgery at other hospitals before they were transferred to our facility for radical repeat-surgery. Twenty-two of them who lacked detailed pathological information of their primary surgeries were excluded; the remaining 20 could provide their pathological reports and were therefore included.

Figure 2.

Characteristic sonographic features of medullary thyroid carcinoma and metastatic lymph nodes. A, Longitudinal ultrasound section of the right thyroid lobe, showing a well-defined hypoechogenic tumor with irregular contours and internal microcalcifications. B, Transverse ultrasound section of the same lesion. C, Central compartment of the same patient, showing ovoid, probably metastatic lymph nodes without hilum. D, Lateral compartment of the same patient, showing ovoid hypoechogenic lesion without echogenic hilum.