A Novel Scoring System for the Risk of Papillary Thyroid Cancer Metastases in Lymph Nodes Posterior to the Right of the Recurrent Laryngeal Nerve

Some surgeons believe that dissection posterior to the right recurrent laryngeal nerve lymph node (PRRLN-LN) is unnecessary for the low metastasis rate and high complication risk. However, persistent metastatic lymph nodes may have a higher recurrence rate, surgical risk, and complications. Thus, it is important to distinguish patients who require PRRLN-LN dissection. To identify the risk factors for lymph nodes posterior to the right recurrent laryngeal nerve metastasis (LN-prRLN) and establish a scoring system to help determine whether PRRLN-LN dissection is required in patients with papillary thyroid carcinoma. 821 participants were randomly allocated to the development and validation cohorts in a 2:1 ratio. A nomogram-based predictive model for LN-prRLN was established based on the risk factors identified in the development cohort. LN-prRLN was diagnosed pathologically in 124 of 821 patients (15.1%) from the entire cohort. Multivariate analysis identified age (odds ratio [OR], 0.964; 95% CI, 0.945-0.983; P < .001), tumor size (OR, 1.536; 95% CI, 1.135-2.079; P = .005), extrathyroidal extension (OR 2.271, 95% CI, 1.368-3.770; P = .002), clinically involved right central compartment lymph node metastasis (OR 1.643, 95% CI, 1.055-2.559; P = .028), and right lateral lymph node metastasis (OR 4.271, 95% CI, 2.325-7.844; P < .001) as the predictors of LN-prRLN. A risk model was established and well validated. Calibration curves to evaluate the nomogram in both the development and validation cohorts revealed a concordance index of 0.756 ± 0.058 and 0.745 ± 0.042, respectively. Our scoring system may be useful for helping the surgeons decide which patients should undergo the dissection of PRRLN-LN.