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.

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