Surgical Treatment of Advanced Thyroid Cancer with Tracheal Invasion

Table 1

Classification of the extent of tracheal invasion in thyroid cancer.

	Shin et al. [8]	McCaffrey [14]
I	Extension through the capsule of the thyroid gland and abutting the external perichondrium	Tumor locates entirely intrathyroidal gland without airway or surrounding muscle invasion
II	Invasion into the cartilage or the cartilaginous layer or destruction of the cartilage	Tumor invades the perichondrium of the aerodigestive tract or firmly abuts the muscle but does not invade into the cartilage or deeply into muscle
III	Extension into the lamina propria of the tracheal mucosa without epithelial invasion	Tumor invades through the airway perichondrium and into the cartilage or deeply into muscle but not into the submucosa
IV	Invasion into or beyond the trachea	Tumor invades through the perichondrium and cartilage or through the muscle and deforms the submucosa but does not penetrate the mucosa
V		Tumor is gross transmucosal involvement