Lateral Neck Lymph Node Characteristics Prognostic of Outcome in Patients with Clinically Evident N1b Papillary Thyroid Cancer

To identify lateral lymph node (LN) characteristics predictive of outcome in papillary thyroid cancer patients with clinically evident nodal disease. A total of 438 patients with lateral neck metastases from papillary thyroid cancer were identified from an institutional database of 3,664 differentiated thyroid cancers. The number of positive LNs, size of the largest LN, number of positive LNs to total number of LNs removed (LN burden), and presence of extranodal spread (ENS) were recorded. Cutoffs for continuous variables were determined by receiver operating characteristic curves. LN variables predictive of recurrence free survival and disease-specific survival (DSS) were identified by the Kaplan-Meier method and the Cox proportional hazard model. The median age was 41 years (range 5-86 years). The median follow-up was 65 months (range 1-332 months). Fifty-nine patients developed disease recurrence; these were local in five, regional in 40, and distant in 30 patients. Fifteen patients died of disease. Receiver operating characteristic cutoffs were > 10 positive LNs and a LN burden > 17 %. No lateral LN characteristics were predictive of DSS. In patients < 45 years old, univariate predictors of recurrence were > 10 positive nodes (p = 0.049) and LN burden > 17 % (p < 0.001). In patients a parts per thousand yen45 years old, > 10 positive nodes, LN burden > 17 %, and presence of ENS were predictive of recurrence (p = 0.019, p = 0.019, and p = 0.029, respectively). LN burden > 17 % (1 positive LN in 6 LNs removed) in the lateral neck is predictive for recurrence in patients of all ages, whereas ENS is also prognostic for recurrence in older patients.