Stage IV is divided into stages IVA, IVB, and IVC. In stage IVA, (1) the tumor has spread through tissue in the lip or oral cavity into nearby tissue and/or bone (jaw, tongue, floor of mouth, maxillary sinus, or skin of chin or nose); cancer may have spread to one lymph node that is 3 centimeters or smaller, on the same side of the neck as the tumor; or (2) the tumor is any size or has spread through tissue in the lip or oral cavity into nearby tissue and/or bone (jaw, tongue, floor of mouth, maxillary sinus, or skin of chin or nose). Cancer has spread to one lymph node on the same side of the neck as the tumor and the lymph node is larger than 3 centimeters but not larger than 6 centimeters, or to more than one lymph node on the same side of the neck as the tumor and the lymph nodes are not larger than 6 centimeters, or to lymph nodes on the opposite side of the neck as the tumor or on both sides of the neck, and the lymph nodes are not larger than 6 centimeters. In stage IVB, (1) the tumor may be any size and has spread to one or more lymph nodes that are larger than 6 centimeters; or (2) the tumor has spread further into the muscles or bones in the oral cavity, or to the base of the skull and/or the carotid artery. Cancer may have spread to one or more lymph nodes anywhere in the neck. In stage IVC, the tumor has spread beyond the lip or oral cavity to distant parts of the body, such as the lungs. The tumor may be any size and may have spread to lymph nodes.