Clinical significance of level VII lymph node metastasis in papillary thyroid cancer

The reclassification of level VII lymph node metastasis (LNM) from N1b to N1a in papillary thyroid carcinoma (PTC) has sparked debate due to limited evidence on its prognostic impact. This study aims to investigate the impact of level VII LNM on cancer-special survival (CSS) in PTC patients. We analyzed data from 40,371 PTC patients in the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2015. The effect of different nodal groups (N0, N1a, N1b and VII) on CSS was evaluated using hazard ratios (HRs) and absolute survival or death probability differences. Cox and Fine-Gray models were employed to estimate HRs with 95% confidence intervals (CIs). Logistic regression analysis was utilized to identify risk factors for level VII LNM. Level VII metastasis was present in 2.0% (817/40,371) of PTC patients. These patients exhibited more aggressive clinicopathological features and received more intensive treatments compared to other nodal groups. Multivariate Cox analysis revealed that level VII LNM was associated with the poorest CSS (adjusted HR for VII vs. N0: 5.67). The adjusted 10-year survival difference between the N0 and VII groups was 2.97%. Independent risk factors for level VII LNM included young age, male gender, white race, large tumor size, extrathyroidal extension and multifocality. Level VII LNM in PTC represents a distinct entity with aggressive clinical behavior and poor prognosis, which suggests the need for tailored clinical management strategies and potential revision of the current N staging system for PTC patients with level VII LNM.