Epithelial tumors are classified according to the International Union Against Cancer (UICC) (3,4).
The T classification represents the extent of the primary tumor.
- T1 – small tumors ≤ 2 cm in largest diameter
- T2 – tumor 2–4 cm in largest diameter
- T3–4 – Advanced tumors with invasion of neighboring organs, soft tissue, bony structures or skin (2).
Tumors of the nasopharynx have a unique T classification.
- T1 – Small tumors confined to nasopharynx
- T2a – Tumor extends to soft tissue of oropharynx and/or nasal cavity without parapharyngeal extension
- T2b – Tumor extends to soft tissue of oropharynx and/or nasal cavity with parapharyngeal extension
- T3 – Tumor invades bony structures and/or paranasal sinuses
- T4 – Tumor with intracranial extension and/or involvement of cranial nerves, infratemporal fossa, hypopharynx, orbit, or masticator space.
The N classification represents metastasis to regional lymph nodes in the neck. The greatest diameter is measured.
- N0 – no regional lymph node metastases
- N1 – single ipsilateral lymph node metastasis ≤ 3 cm
- a – single ipsilateral lymph node metastasis > 3 cm ≤ 6 cm
- b – multiple ipsilateral lymph node metastases ≤ 6 cm
- c – bilateral or contralateral lymph node metastases ≤ 6 cm
- N3 – lymph node metastases > 6 cm
The M classification represents distant metastases.
- M0 – no distance metastases
- M1 – distant metastases