Predictive factors of contralateral paratracheal lymph node metastasis in papillary thyroid cancer: prospective multicenter study.

OBJECTIVE To analyze patterns of central lymph node (LN) metastasis to specific compartments in the neck and predictive factors of contralateral paratracheal LN metastasis in patients who underwent prophylactic bilateral central LN dissection for papillary thyroid cancer (PTC). STUDY DESIGN Prospective study. SETTING Multitertiary centers. SUBJECTS AND METHODS One hundred forty consecutive patients underwent total thyroidectomy and prophylactic bilateral central LN dissection for unilateral PTC without evidence of central LN metastatic disease based on preoperative ultrasound imaging. The central LN compartment was divided into prelaryngeal, ipsilateral/contralateral paratracheal, and pretracheal regions. The patterns of central LN metastasis and clinicopathologic variables for predicting contralateral metastasis were analyzed. RESULTS Fifty-one (36.4%) of 140 patients had nodal involvement in the central compartment. Twelve (23.5%) patients had ipsilateral paratracheal LN metastasis, 17 (33.3%) had ipsilateral paratracheal and pretracheal LN metastasis, 14 (27.5%) had bilateral paratracheal LN metastasis, 9 (17.6%) had pretracheal-only LN metastasis, and 8 (15.7%) had prelaryngeal LN metastasis. Ipsilateral paratracheal LN metastasis was found to independently predict contralateral paratracheal LN metastasis in patients without central LN metastatic disease. CONCLUSIONS Contralateral paratracheal LN metastasis is associated with ipsilateral paratracheal LN metastasis. This information may help to determine the optimal extent of prophylactic central LN dissection in patients with PTC.