Chapter 084. Head and Neck Cancer (Part 4) Table 84-2 Definition of TNM–Nasopharynx Primary Tumor (T) Stage Grouping TX Cannot be assessed Stage 0 Tis N0 M0 T0 No evidence Stage I T1 N0 M0 Tis Carcinoma in situ Stage IIA T2a N0 M0 T1 Tumor conf ined to the nasopharynx Stage IIB T1 N1 M0 T2 Tumor extends to soft tissues T2 N1 M0 T2a Tumor extends to the oropharynx and/or nasal cavity w/o parapharyngeal extension T2a N1 M0 T2b Any tumor with parapharyngeal extension T2b N1 M0 T3 Tumor involves bony structures and/or paranasal sinuses T2b N1 M0 T4 Stage III T1 N2 M0 Tumor with intracranial extension and/or involvement of cranial nerves, infratemporal fossa, hypopharynx, orbit, or masticator space T2a N2 M0 Regional Lymph No des (N) T2b N2 M0 The distribution and the prognostic impact of regional lymph node spread from nasopharynx cancer, particularly of the undifferentiated type, are different from those of other head and neck mucosal cancers and justify the use of a diff erent N classification scheme. T3 N0 M0 NX Regional lymph nodes cannot be assessed T3 N1 M0 N0 No regional lymph node metastasis T3 N2 M0 N1 Unilateral metastasis in lymph node(s), ≤6 cm in greatest dimension, above the supraclavicular fossa T4 N0 M0 N2 Bilateral metastasis in lymph node(s), ≤6 cm in greatest dimension, above the supraclavicular fossa T4 N1 M0 N3 Metastasis in lymph no de(s), >6 cm and/or to supraclavicular fossa T4 N2 M0 N3a Greater than 6 cm in dimension Any T N3 M0 N3b Extension to the supraclavicular fossa Any T Any N M1 In patients with lymph node involvement and no visible primary, the diagnosis should be made by lymph node excision. If the results indicate squamous cell carcinoma, a panendoscopy should be performed, with biopsy of all suspicious-appearing areas and directed biopsies of common primary sites, such as the nasopharynx, tonsil, tongue base, and pyriform sinus. . Chapter 084. Head and Neck Cancer (Part 4) Table 84-2 Definition of TNM–Nasopharynx Primary Tumor (T) Stage. lymph node spread from nasopharynx cancer, particularly of the undifferentiated type, are different from those of other head and neck mucosal cancers and justify the use of a diff erent. extension and/ or involvement of cranial nerves, infratemporal fossa, hypopharynx, orbit, or masticator space T2a N2 M0 Regional Lymph No des (N) T2b N2 M0 The distribution and the