Methods
Subgroup analysis was performed on three distinct groups (staging in
brackets is according to the AJCC 8th edition on
thyroid cancer):
- Gross ETE involving only strap muscles (T3b)
- Gross ETE with minimal tracheal invasion with or without strap muscle
involvement (T4a)
- Gross ETE with involvement of neck structures (RLN, larynx, esophagus,
subcutaneous tissue) with or without tracheal invasion (T4a)