Stage IV oropharyngeal cancer is divided into stages IVA, IVB, and IVC. In stage IVA, the cancer either: (1) has spread to tissues near the oropharynx, including the voice box, roof of the mouth, lower jaw, muscle of the tongue, or central muscles of the jaw, and may have spread to one or more nearby lymph nodes, none larger than 6 centimeters; OR (2) is any size and has spread to one lymph node that is larger than 3 centimeters but not larger than 6 centimeters on the same side of the neck as the cancer, or to more than one lymph node, none larger than 6 centimeters, on one or both sides of the neck. In stage IVB, the cancer either: (1) surrounds the main artery in the neck or has spread to bones in the jaw or skull, to muscle in the side of the jaw, or to the upper part of the throat behind the nose, and may have spread to nearby lymph nodes; OR (2) has spread to a lymph node that is larger than 6 centimeters and may have spread to tissues around the oropharynx. In stage IVC, cancer has spread to other parts of the body; the tumor may be any size and may have spread to lymph nodes.