Pretracheal-laryngeal lymph nodes in frozen section predicting contralateral paratracheal lymph nodes metastasis

Background: There has been an ongoing debate concerning the predictors of contralateral paratracheal lymph nodes metastasis (LNM) in unilateral papillary thyroid cancer (PTC). This study aimed to explore the value of pretracheal-laryngeal lymph nodes (LNs) in frozen section in predicting contralateral paratracheal LNM.

Methods: A total of 242 patients with unilateral PTC were enrolled in this prospective study. Patients who underwent total thyroidectomy and bilateral central lymph nodes dissection (LND) were divided into two groups according to positive or negative contralateral paratracheal LNs. Patients' demographics and clinicopathological features were compared between the two groups. Validity indexes and consistency of pretracheal-laryngeal LNs in frozen sections were calculated.

Results: LNM rates in central, ipsilateral paratracheal, pretracheal-laryngeal, and contralateral paratracheal regions were 55.37%, 47.03%, 23.55% and 14.05%, respectively. Only pretracheal-laryngeal LNM, regardless of whether detected in frozen or paraffin sections, were independent risk factors for contralateral paratracheal LNM (OR = 2.707; 95% CI 1.062-6.902; P = 0.037 in frozen section; OR = 3.072; 95% CI 1.248-7.560; P = 0.015 in paraffin section). The sensitivity, specificity, false-negative rate, false-positive rate, accuracy rate, and Kappa value of pretracheal-laryngeal LNM in frozen sections for predicting pretracheal-laryngeal LNM were 87.72%, 100%, 12.28%, 0%, 97.11% and 0.916 respectively, while those for predicting contralateral paratracheal LNM were 85,29%, 89.90%, 14.71%, 10.10%, 89.22%, and 0.618 respectively.

Conclusion: Pretracheal-laryngeal LNs in frozen section accurately predicted contralateral paratracheal LNM, which could allow the identification of patients who can benefit from an extended central LND.