Central lymph node metastasis of unilateral papillary thyroid carcinoma: patterns and factors predictive of nodal metastasis, morbidity, and recurrence.

BACKGROUND: Although subclinical cervical lymph node (LN) metastases in papillary thyroid carcinoma (PTC) are common, the efficacy of prophylactic central LN dissection (CLND) is unclear. Few prospective studies have assessed the relationships between complete pathologic information regarding tumors and metastatic nodes in the central compartment. We therefore investigated the pattern and predictive indicators of central LN metastasis, morbidity, and recurrence in patients who underwent total thyroidectomy and prophylactic CLND for unilateral PTC and clinically node-negative neck (cN0) disease.
METHODS: This prospective study involved 184 patients with previously untreated unilateral PTC and cN0 who underwent total thyroidectomy and bilateral CLND. Nodal samples were divided into the prelaryngeal/pretracheal and ipsilateral and contralateral paratracheal regions, with each assessed for clinicopathologic predictors of central metastases. Postoperative morbidity and recurrence were assessed.
RESULTS: Rates of metastasis to ipsilateral and contralateral central compartments were 42.9 and 9.8%, respectively. Multivariate analysis showed that tumor size >1 cm and extrathyroidal extension were independent predictors of ipsilateral metastasis, and ipsilateral metastases independently predicted contralateral metastases (P < 0.05 each). Permanent hypoparathyroidism and incidental recurrent nerve paralysis were found in 1.6 and 0% of patients, respectively. After a mean follow-up of 46 months, none of these patients had recurrence in the central compartment.
CONCLUSIONS: Subclinical metastases are highly prevalent in the ipsilateral central neck of patients with PTC >1 cm. Contralateral central metastases, although uncommon, are associated with ipsilateral central metastases. These findings may guide the necessity and extent of prophylactic bilateral or unilateral CLND.