Stage IVB includes: (T4b, Any N, M0); (Any T, N3, M0). T4b: Supraglottis: Very advanced local disease. Tumor invades prevertebral space, encases carotid artery, or invades mediastinal structures. Glottis: Very advanced local disease. Tumor invades prevertebral space, encases carotid artery, or invades mediastinal structures. Subglottis: Very advanced local disease. Tumor invades prevertebral space, encases carotid artery, or invades mediastinal structures. N3: Metastasis in a lymph node, more than 6 cm in greatest dimension. M0: No distant metastasis. (AJCC 7th ed.) [from NCI]