Stage IVB includes: (Any T, N3, M0); (T4b, Any N, M0). T4b: Lip and oral cavity cancer with very advanced local disease. Tumor invades masticator space, pterygoid plates, or skull base and/or encases internal carotid artery. N3: Metastasis in a lymph node more than 6 cm in greatest dimension. M0: No distant metastasis. (AJCC 7th ed.) [from
NCI]