Definition

Stage IV is divided into stages IVA and IVB, depending on where the cancer has spread. In stage IVA, cancer has spread (1) into the diaphragm, pleura, sac around the heart, azygos vein, or peritoneum. Cancer is found in 3 to 6 lymph nodes near the tumor; or (2) into nearby structures, such as the aorta, airway, or spine. Cancer may be found in 0 to 6 lymph nodes near the tumor; or (3) to 7 or more lymph nodes near the tumor. In stage IVB, cancer has spread to other parts of the body, such as the liver or lung.