Thyroid Cancer Research

Proposed Thyroid-Specific TNM System Reclassifies 36.6% of Poorly Differentiated Thyroid Cancers, With Level VII Nodes Upgraded to N1c and a Modest Gain in Discrimination

In an international cohort of 1010 patients with poorly differentiated thyroid carcinoma (PDTC) from 91 centers in 14 countries, the authors propose a PDTC-specific TNM staging system that removes the 55-year age cutoff and classifies level VII (upper mediastinal) nodal disease as a new N1c category. The proposed system reclassified 370 patients (36.6%) relative to TNM-8 (DTC criteria). Level VII lymph node metastasis carried the worst 5-year overall survival, 45.2% (95% CI, 33.4-61.2).