Table 3.

TNM staging classification (AJCC Cancer Staging Manual, 8th; 2017)

Primary tumor (T)

TX primary tumor cannot be assessed

T0 no tumor identified, but EBV-positive cervical node(s) involvement

T1s carcinoma in situ

T1: tumor confined to the nasopharynx, or tumor extends to oropharynx and/or nasal cavity without parapharyngeal extension

T2: tumor with extension to parapharyngeal space and/or infiltration of the medial pterygoid, lateral pterygoid, and/or prevertebral muscles

T3: tumor invades bony structures of skull base cervical vertebra, pterygoid structures, and/or paranasal sinuses

T4: tumor with intracranial extension and/or involvement of cranial nerves, hypopharynx, orbit, parotid gland and/or infiltration beyond the lateral surface of the lateral pterygoid muscle

Regional lymph nodes (N)

NX: regional lymph nodes cannot be assessed

N0: no regional lymph nodes metastasis

N1: unilateral metastasis, in cervical lymph node(s), and/or unilateral, or bilateral metastasis in retropharyngeal lymph nodes, 6 cm or less, above the caudal border of cricoid cartilage

N2: bilateral metastasis in cervical lymph node(s), 6 cm or less above the caudal border of cricoid cartilage

N3: metastasis in cervical lymph node(s) greater than 6 cm in dimension and/or extension below the caudal border of cricoid cartilage

Distant metastasis (M)

M0: no distant metastasis

M1: distant metastasis