Stage III non-small cell lung cancer is divided into stages IIIA and IIIB. In stage IIIA, cancer has spread to lymph nodes on the same side of the chest as the tumor. Also, (1) the tumor may be any size; (2) part of the lung (where the trachea joins the bronchus) or the whole lung may have collapsed or become inflamed; (3) there may be one or more separate tumors in the same lobe of the lung; and/or (4) cancer may have spread to any of the following: main bronchus (but not the area where the trachea joins the bronchus), chest wall, diaphragm and the nerve that controls it, or membrane around the heart, lung, or lining the chest wall. OR in stage IIIA, cancer has spread to lymph nodes on the same side of the chest as the tumor. Also, (1) the tumor may be any size; (2) the whole lung may have collapsed or become inflamed; (3) there may be one or more separate tumors in any of the lobes of the lung with cancer; and/or (4) cancer may have spread to any of the following: main bronchus (but not the area where the trachea joins the bronchus), chest wall, diaphragm and the nerve that controls it, membrane around the lung or lining the chest wall, heart or the membrane around it, trachea, carina (where the trachea joins the bronchi), esophagus, sternum (chest bone), backbone, major blood vessels that lead to or from the heart, or the nerve that controls the larynx (voice box). OR in stage IIIA, cancer has not spread to the lymph nodes and the tumor may be any size. Cancer has spread to any of the following: trachea, carina, esophagus, sternum, backbone, heart, major blood vessels that lead to or from the heart, or the nerve that controls the larynx.