CS Extension: Thyroid Gland

Note: AJCC considers all anaplastic carcinomas to be T4.Collaborative Staging has implemented this as follows:If histology is equal to 8020 or 8021 and if CS Extension is equal to 00, 10, 20, 30, 40, 45, or 48, then T category is equal to T4a.For these histologies, if CS Extension is equal to 50, 52, 60, 62, 70, 72, or 80, then T category is equal to T4b.If CS Extension is equal to 95 or 99, the T category is T4NOS. For all other histologies, follow the rules as shown in the tables.

Code	Description	TNM	SS77	SS2000
00	In situ; non-invasive	Tis	IS	IS
10	Single invasive tumor confined to thyroid	*	L	L
20	Multiple foci confined to thyroid	*	L	L
30	Localized, NOS	*	L	L
40	Into thyroid capsule, but not beyond	*	L	L
45	Minimal extrathyroid extension including: Strap muscle(s): Omohyoid Sternohyoid Sternothyroid	T3	RE	RE
48	Pericapsular soft/connective tissue	T3	RE	RE
50	Parathyroid Nerves: Recurrent laryngeal Vagus	T4a	RE	RE
52	Cricoid cartilages Esophagus Larynx Sternocleidomastoid muscle	T4a	RE	RE
60	Thyroid cartilage Tumor is described as "FIXED to adjacent tissues"	T4b	RE	RE
62	Blood vessel(s) (major): Carotid artery Jugular vein Thyroid artery or vein	T4b	RE	RE
70	Bone Skeletal muscle, other than strap or sternocleidomastoid muscle	T4b	D	D
72	Trachea	T4a	D	D
80	Further contiguous extension Mediastinal tissues Prevertebral fascia	T4b	D	D
95	No evidence of primary tumor	T0	U	U
99	Unknown extension Primary tumor cannot be assessed Not documented in patient record	TX	U	U

* For Extension codes 10, 20, 30, and 40 ONLY, the T category is assigned based on value of CS Tumor Size from Extension Size Table.