TNM Staging of Lip and Oral Cavity cancers – AJCC 8th Edition

The recently released 8th edition of the American Joint Committee on Cancer (AJCC) Staging Manual, Head and Neck Section, introduces significant modifications from the prior 7th edition.

In this article, we discuss the changes in the 8th edition of AJCC staging manual for oral cavity cancers.

T Staging

For T staging of the oral cavity cancers, T4a and T4b are added in new TNM staging.

T4a is moderately advanced local disease: lip, tumor invades through cortical bone or involves the inferior alveolar nerve, floor of the mouth or skin of the face (i.e. chin or nose).

T4b is a very advanced local disease, tumor invades masticator space and pterygoid plates or skull base encases the internal carotid artery.

Primary Tumor (T)
T Category T Criteria
Tx Primary tumor cannot be assessed
Tis Carcinoma in situ
T1 Tumor ≤2 cm, ≤5 mm depth of invasion (DOI).
DOI is the depth of invasion and not tumor thickness.
T2 Tumor ≤2 cm, DOI >5 mm and ≤10 mm; or
Tumor >2 cm but ≤4 cm, and ≤10 mm DOI
T3 Tumor >4 cm; or
Any tumor >10 mm DOI
T4 T4a Moderately advanced local disease
LIP: Tumor invades through cortical bone or involves the inferior alveolar nerve, the floor of mouth, or skin of the face (ie, chin or nose).
ORAL CAVITY: 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 the internal carotid artery.

N Staging

In the new edition of TNM Staging for oral cavity cancers, there are now separate classifications for clinical and pathological neck nodes for all subsites.

In the clinical stage of N category (cN) for all cancers, except viral related cancers and mucosal melanoma, extranodal cancer extension (ENE) has been added to the lymph node category (N).

N3a and N3b are now added. N3a being metastasis in a lymph node larger than 6 cm in greatest dimension and ENE negative and N3b being metastasis in any node (s) and clinically overt ENE positive.

Regional Lymph Nodes (N)
N Category Clinical N (cN) criteria Pathological N (pN) Criteria
Nx Regional lymph nodes cannot be assessed Regional lymph nodes cannot be assessed
N0 No regional lymph node metastasis No regional lymph node metastasis
N1 Metastasis in a single ipsilateral lymph node, 3 cm or smaller in greatest dimension with no extranodal extension ENE(–) Metastasis in a single ipsilateral lymph node, 3 cm or smaller in greatest dimension with no extranodal extension ENE(–)
N2 N2a Metastasis in a single ipsilateral node larger than 3 cm but not larger than 6 cm in greatest dimension and ENE(–) A single ipsilateral node larger than 3 cm but not larger than 6 cm in greatest dimension and ENE(–); or
Metastasis in a single ipsilateral lymph node, 3 cm or smaller in greatest dimension and ENE(+)
N2b Metastasis in multiple ipsilateral nodes, none larger than 6 cm in greatest dimension, and ENE(–) Metastasis in multiple ipsilateral nodes, none larger than 6 cm in greatest dimension and ENE(–)
N2c Metastasis in bilateral or contralateral lymph nodes, none larger than 6 cm in greatest dimension, and ENE(–) Metastasis in bilateral or contralateral lymph node(s), none larger than 6 cm in greatest dimension and ENE(–)
N3 N3a Metastasis in a lymph node larger than 6 cm in greatest dimension and ENE(–) Metastasis in a lymph node larger than 6 cm in greatest dimension and ENE(–)
N3b Metastasis in any node(s) and clinically overt ENE(+) Metastasis in a single ipsilateral node larger than 3 cm in greatest dimension and ENE(+); or
Multiple ipsilateral, contralateral, or bilateral nodes any with ENE(+); or
A single contralateral node 3 cm or smaller and ENE(+)
NOTE: A designation of “U” or “L” may be used for any N category to indicate metastasis above the lower border of the cricoid (U) or below the lower border of the cricoid (L).

Similarly, clinical and pathological ENE should be recorded as ENE(–) or ENE(+).

M Staging

Previous Mx (distant metastasis which cannot be assessed) category has been dropped in the eighth version of AJCC 8 TNM staging.

Distant Metastasis (M)
M Category M Criteria
M0 No distant metastasis
M1 Distant metastasis

Prognostic stage grouping

Based on the above, TNM prognostic stage groups are defined as follows.

Prognostic Stage Groups
Stage T N M
Stage 0 Tis N0 M0
Stage I T1 N0 M0
Stage II T2 N0 M0
Stage III  T3 N0 M0
T1,2,3 N1 M0
Stage IVA  T4a N0, 1 M0
T1,2,3,4a N2 M0
Stage IVB T4b Any N M0
Any T N3 M0
Any T Any N M1

References

  1. Gospodarowicz MK, Brierley JD, Wittekind C, editors. TNM classification of malignant tumours. John Wiley & Sons; 2017 Jan 17.
  2. Lydiatt WM, Patel SG, O’Sullivan B, Brandwein MS, Ridge JA, Migliacci JC, Loomis AM, Shah JP. Head and neck cancers—major changes in the American Joint Committee on cancer eighth edition cancer staging manual. CA: a cancer journal for clinicians. 2017 Mar 1;67(2):122-37.

Meet the author

Dr Sanu P Moideen is an Indian-born oto-rhino-laryngologist (ENT) based in Cochin, Kerala, India. He is currently working as Post-Doctoral Fellow in Head and Neck Oncology at Regional Cancer Center, Trivandrum, Kerala.

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