stage IVB

Definition of stage IVB anaplastic thyroid cancer
National Cancer Institute

stage IVB anaplastic thyroid cancer

(... A-nuh-PLAS-tik THY-royd KAN-ser)
Stage IV is divided into stages IVA, IVB, and IVC. In stage IVB, one of the following is found: (1) cancer is found in the thyroid and the tumor may be any size; cancer has spread to nearby lymph nodes; or (2) the tumor is any size and cancer has spread from the thyroid to nearby muscles in the neck and may have spread to nearby lymph nodes; or (3) the tumor is any size and cancer has spread from the thyroid to soft tissue under the skin, the esophagus, the trachea, the larynx, the recurrent laryngeal nerve (a nerve that goes to the larynx), or tissue in front of the spine, or cancer has surrounded the carotid artery or the blood vessels in the area between the lungs; cancer may have spread to lymph nodes.

Source: NCI Dictionary of Cancer Terms