I

T1

N0

M0

II

T2

N0

M0

III

T3 or

N0

M0

T1–3

N1

M0

IVA

T1–3

N2

M0

T4a

N0–2

M0

IVB

T4b

Any N

M0

Any T

N3

M0

IVC

Any T

Any N

M1

* Definition of Primary Tumor (T)

T1

Tumor ≤ 2 cm with DOI (depth of invasion, not tumor thickness) ≤ 5 mm

T2

Tumor ≤ 2 cm with DOI > 5 mm OR tumor > 2 cm and ≤ 4 cm with DOI ≤ 10 mm

T3

Tumor > 2 cm and ≤4 cm with DOI > 10 mm OR tumor > 4 cm with DOI ≤ 10 mm

T4a

Moderately advanced local disease

Lip: Tumor invades through cortical bone or involves the inferior alveolar nerve, floor of mouth, or skin of face (eg, chin or nose)

Oral cavity: Tumor > 4 cm with DOI > 10 mm OR tumor invades adjacent structures only (eg, through cortical bone of the mandible or maxilla, or involves the maxillary sinus or skin of the face)

Note: Superficial erosion of bone/tooth socket (alone) by a gingival primary is not sufficient to classify a tumor as T4.

T4b

Very advanced local disease

Tumor invades masticator space, pterygoid plates, or skull base and/or encases internal carotid artery

† Definition of Regional Lymph Node (N)

N1

Metastasis in a single ipsilateral node ≤ 3 cm and no extranodal extension

N2

Metastasis in single ipsilateral node > 3 cm but ≤ 6 cm and no extranodal extension; OR in multiple ipsilateral nodes ≤ 6 cm and no extranodal extension; OR in bilateral or contralateral nodes ≤ 6 cm and no extranodal extension

N3

Metastasis in a node > 6 cm and no extranodal extension; OR in any nodes and extranodal extension

‡ Definition of Distant Metastasis (M)

M0

No distant metastasis

M1

Distant metastasis