Definition

Stage IV is divided into stages IVA, IVB, and IVC. In stage IVB, the tumor (1) has spread to one lymph node that is larger than 6 centimeters; or (2) has spread to one lymph node that is larger than 3 centimeters, on the same side of the neck as the primary tumor, and cancer has spread through the outside covering of the lymph node into nearby connective tissue; or (3) has spread to one lymph node of any size on the opposite side of the neck as the primary tumor, and cancer has spread through the outside covering of the lymph node into nearby connective tissue; or (4) has spread to multiple lymph nodes anywhere in the neck, and cancer has spread through the outside covering of any lymph node into nearby connective tissue; or (5) has spread further into the muscles or bones needed for chewing, or to the part of the sphenoid bone behind the upper jaw, and/or to the carotid artery near the base of the skull. Cancer may have also spread to one or more lymph nodes of any size, anywhere in the neck.