Table 2.

Study variables: gradation by severity of pathohistological features of tumor aggressiveness, intraglandular dissemination, and locoregional metastatic spread.

Gradation	Variables
	Pathological aggressiveness of primary tumor	Intraglandular dissemination (multicentricity)	Neck dissection*	Locoregional metastatic spread
Grade I	Sharply demarcated; encapsulated	No multicentric foci	Not done	No metastatic spread
Grade II	No clear tumor border; tumor capsule invasion	Ipsilateral lobe spread	Paratracheal	Paratracheal
Grade III	Perivascular, perineural spread; penetration of adjacent soft tissues; fat tissue, muscle, cartilage invasion	Bilateral/Contralateral lobe spread	Paratracheal and Lateral	Paratracheal and Lateral

*Neck dissection classification from: Robbins et al. [12].