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.
|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|
|40||Into thyroid capsule, but not beyond||*||L||L|
|45||Minimal extrathyroid extension including:
|48||Pericapsular soft/connective tissue||T3||RE||RE|
Tumor is described as "FIXED to adjacent tissues"
|62||Blood vessel(s) (major):
|95||No evidence of primary tumor||T0||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.