Differentiated Thyroid Cancer: The Role of ATA Nodal Risk Factors in N1b Patients

Objectives/Hypothesis: Nodal involvement is frequent in patients with differentiated thyroid cancers (DTCs), but its prognostic relevance is not univocal. Some characteristics of nodal metastases can increase the risk of recurrence. We attempted to quantify the impact on survival of nodal factors included in the American Thyroid Association (ATA) risk stratification system in N1b patients with DTC. Study Design: Retrospective study. Methods: A retrospective analysis of patients affected by DTC who underwent therapeutic lateral neck dissection (ND) was performed. The impact on the prognosis of the number of positive lymph nodes (LNs), dimension of nodal metastasis, and microscopic and macroscopic extranodal extension (miENE and maENE, respectively) was investigated. Results: The study included 347 N1b patients who underwent 401 therapeutic lateral NDs. Mean number of positive LNs was nine, mean nodal ratio was 0.27, and mean diameter of metastasis was 15.5 mm. ENE was detected in 25.9% of patients (22.5% miENE and 3.5% maENE). In univariate analysis, the presence of maENE had an impact on disease specific survival (DSS) (P =.023); increasing number of positive LNs affected DSS and locoregional control (LRC) (P =.009 and =.006, respectively); increasing metastatic node dimension was a risk factors for overall survival, DSS, and metastases free survival (MFS) (P =.05, =.013 and =.016). In multivariate analysis, number of positive LNs and LN dimension were independent risk factors for LRC and MFS, respectively (HR 1.1, P =.028; HR 1.1, P =.026). Conclusions: In our analysis on a cohort of N1b patients, the number of positive LNs and LN dimension were confirmed as independent risk factors for locoregional and distant recurrence, respectively. Level of Evidence: 4 Laryngoscope, 2020.