Tumor definitions for nasopharyngeal carcinomaa
| T Category | T Criteria |
|---|---|
| Tx | Primary tumor cannot be assessed |
| T0 | No tumor identified, but EBV+ cervical lymph node(s) involvement |
| Tis | In situ carcinoma |
| T1 | Tumor confined to nasopharynx, or extension to oropharynx and/or nasal cavity without parapharyngeal involvement |
| T2 | Tumor with extension to parapharyngeal space, and/or adjacent soft-tissue involvement (medial pterygoid, lateral pterygoid, prevertebral muscles) |
| T3 | Tumor with infiltration of bony structures at skull base, cervical vertebrae, pterygoid structures, and/or paranasal sinuses |
| T4 | Tumor with intracranial extension, involvement of cranial nerves, hypopharynx, orbit, parotid gland, and/or extensive soft-tissue infiltration beyond the lateral surface of the lateral pterygoid muscle |
↵a The eighth edition shows critical changes from the prior edition with downstaging of masticator space involvement from T4 to T2 and clarification of the T-staging for invasion of bony structures. Table adapted with permission of the American Joint Committee on Cancer, Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual.1