TNM Staging Classification for Carcinoma of the Tongue (Oral Cavity)
Carcinoma of the tongue is staged using the AJCC 8th edition TNM definitions for oral cavity tumors, in which the T category incorporates both tumor size and depth of invasion (DOI). [1] Distant metastasis is classified as M0 (none) or M1 (present). [1]
Tumor (T) Category Definitions
- TX: Primary tumor cannot be assessed. [1]
- Tis: Carcinoma in situ. [1]
- T1: Tumor ≤2 cm with DOI ≤5 mm. [1]
- T2: Tumor ≤2 cm with DOI >5 mm, or tumor >2 cm and ≤4 cm with DOI ≤10 mm. [1]
- T3: Tumor >2 cm and ≤4 cm with DOI >10 mm, or tumor >4 cm and ≤10 mm. [1]
- T4: Moderately advanced or very advanced local disease. [1]
- T4a: 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). [1]
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T4b: Tumor invades masticator space, pterygoid plates, or skull base and/or encases the internal carotid artery. [1]
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Note: Superficial erosion of bone/tooth socket alone from a gingival primary is not sufficient to classify as T4. [1]
Nodal (N) Category Definitions
- NX: Regional lymph nodes cannot be assessed. [1]
- N0: No regional lymph node metastasis. [1]
- N1: Metastasis in a single ipsilateral lymph node ≤3 cm in greatest dimension and ENE(–). [1]
- N2: Metastasis patterns described by AJCC 8th edition, including ENE(–) and size-based criteria. [1]
- N2a: Single ipsilateral node ≤3 cm with ENE(+), or single ipsilateral node >3 cm but ≤6 cm with ENE(–). [1]
- N2b: Multiple ipsilateral nodes, none >6 cm with ENE(–). [1]
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N2c: Bilateral or contralateral nodes, none >6 cm with ENE(–). [1]
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N3: Metastasis patterns described by AJCC 8th edition, including size and/or ENE(+). [1]
- N3a: Lymph node >6 cm with ENE(–). [1]
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N3b: Includes ENE(+) with specified nodal patterns and sizes. [1]
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ENE = extranodal extension. [1]
Metastasis (M) Category Definitions
- M0: No distant metastasis. [1]
- M1: Distant metastasis. [1]
Practical Staging Mapping for Tongue Carcinoma
- The T category requires determination of tumor greatest dimension and depth of invasion (DOI). [1]
- The N category incorporates lymph node size, laterality, and extranodal extension (ENE). [1]
- The M category is based on presence versus absence of distant metastatic disease. [1]
Notes on DOI and Classification
- DOI is depth of invasion and not tumor thickness. [1]
- Clinical and pathological DOI are used with size to determine the T category. [1]
Lymph Node Level Qualifiers
- 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). [1]
Nodal Qualifiers for ENE
- Clinical and pathological ENE should be recorded as ENE(–) or ENE(+). [1]