Stage IVB includes: (T4b, Any N, M0); (Any T, N3, M0). T4b: Tumor with very advanced local disease. Tumor invades lateral pterygoid muscle, pterygoid plates, lateral nasopharynx, or skull base or encases carotid artery. N3: Tumor with metastasis in a lymph node more than 6 cm in greatest dimension. M0: No distant metastasis. (AJCC 7th ed.) [from NCI]