Collaborative Stage

Note 1: AJCC considers all anaplastic carcinomas to be T4.
Note 2: AJCC considers "in situ carcinoma of thyroid gland" an impossible diagnosis. Any case so coded is mapped to TX for AJCC stage and in situ Summary Stage.
Note 3: The assignment of T1 and T2 categories for carcinoma of the thyroid is based on tumor size. A physician's statement of the T category may be used to code both CS Tumor Size and/or CS Extension if this is the only information in the medical record regarding one or both of these fields. However the two fields are coded independently; for example, the record may document size but not extension. Use codes 405, 410, 415, 420, 490, 560, 810, and 815 as appropriate to code CS Extension based on a statement of T when no other extension information is available.
Note 4: Use code 300 for localized tumor only if no information is available to assign codes 100, 200, 400, 405, 410, 415, 420, or 490.
Note 5: Extension codes 405, 410, 415, 420, and 490 are not compatible with anaplastic carcinomas of the thyroid.

^ For CS Extension codes 000, 100-550, 950, and 999 ONLY, the T category for AJCC 7 staging is assigned based on the value of CS Tumor Size and/or CS Extension as shown in the Extension Size AJCC 7 Table for all histologies except 8020, 8021, 8030, 8031, and 8032, or any other histology with grade equal to 4. For these histologies or grade 4, the T category is assigned based on the value of CS Extension as shown in the Histology Grade Extension AJCC Table.
* For CS Extension codes 000, 100-550, 950, and 999 ONLY, the T category for AJCC 6 staging is assigned based on the value of CS Tumor Size and/or CS Extension as shown in the Extension Size AJCC 6 Table AJCC 6 for all histologies except 8020, 8021, 8030, 8031, and 8032, or any other histology with grade equal to 4. For these histologies or grade 4, the T category is assigned based on the value of CS Extension as shown in the Histology Grade Extension AJCC Table.
** For CS Extension code 560 ONLY, the value for SS1977 and SS2000 is assigned based on the value of histology and grade as shown in the Histology Grade Extension Summary Stage Table.

Code	Description	TNM 7 Map	TNM 6 Map	SS77 Map	SS2000 Map
000	In situ, intraepithelial, non-invasive	^	*	IS	IS
100	Single invasive tumor confined to thyroid	^	*	L	L
200	Multiple foci confined to thyroid	^	*	L	L
300	Localized, NOS	^	*	L	L
400	Into thyroid capsule, but not beyond	^	*	L	L
405	Stated as T1a with no other information on extension	^	*	L	L
410	Stated as T1b with no other information on extension	^	*	L	L
415	Stated as T1 [NOS] with no other information on extension	^	*	L	L
420	Stated as T2 with no other information on extension	^	*	L	L
450	Minimal extrathyroid extension including: Strap muscle(s): Omohyoid Sternohyoid Sternothyroid Thyrohyoid	^	*	RE	RE
480	Pericapsular soft tissue/connective tissue	^	*	RE	RE
490	Stated as T3 with no other information on extension	^	*	L	L
500	Parathyroid Nerves: Recurrent laryngeal Vagus	^	*	RE	RE
520	Cricoid cartilage Esophagus Larynx Sternocleidomastoid muscle	^	*	RE	RE
550	Trachea	^	*	D	D
560	Stated as T4a with no other information on extension	T4a	T4a	**	**
600	Thyroid cartilage Tumor described as "FIXED to adjacent tissues"	T4b	T4b	RE	RE
620	Blood vessel(s) (major): Carotid artery (encased) Jugular vein Thyroid artery or vein	T4b	T4b	RE	RE
650	(600 or 620) + 550 Any structures in code 600 or 620 plus trachea	T4b	T4b	D	D
700	Bone Skeletal muscle, other than strap or sternocleidomastoid muscle	T4b	T4b	D	D
720	OBSOLETE DATA CONVERTED V0200 See code 550 Trachea	ERROR	ERROR	ERROR	ERROR
730	700 + 550 Any structures in code 700 plus trachea	T4b	T4b	D	D
800	Further contiguous extension including: Mediastinal tissues Prevertebral fascia	T4b	T4b	D	D
810	Stated as T4b with no other information on extension	T4b	T4b	D	D
815	Stated as T4 [NOS] with no other information on extension	T4NOS	T4NOS	RE	RE
950	No evidence of primary tumor	^	*	U	U
999	Unknown; extension not stated Primary tumor cannot be assessed Not documented in patient record	^	*	U	U

Thyroid

CS Extension