To plan the right treatment for your lung cancer, your doctor will want to find out the size of your tumor and where it is located. Your doctor will also want to know if your lung cancer has spread to your lymph nodes or other parts of the body. This is known as staging.

The earliest stage of lung cancer is stage 0. Other stages are stage I (one), stage II (two), stage III (three) and stage IV (four). The lowest number means the cancer has spread less or not at all. The higher numbers mean the cancer has spread to many places in your body.

The following information from the National Cancer Institute is a summary of the stages for non-small cell lung cancers. Non-small cell cancer is the most common type of lung cancer.

Stage 0
Abnormal cells are found in the lining of the airways. These abnormal cells may become cancer. This cancer may spread into nearby normal tissues. Your doctor may refer to this stage as adenocarcinoma in situ or squamous cell carcinoma in situ.

Stage I
In this stage, cancer has formed. The tumor is in the lung only. It is about 3-4 centimeters in size. Cancer has not spread to the lymph nodes. Part of the lung or the whole lung may have collapsed or developed pneumonitis, or inflammation of the lung.

Stage II
In this stage, the tumor is about 4-5 centimeters in size. Part of the lung or the whole lung may have collapsed or developed pneumonitis. Cancer may have spread to lymph nodes on the same side of the chest as the primary tumor.

Stage III
In this stage, the tumor may be about 5-7 centimeters or any size. Part of the lung or the whole lung may have collapsed or developed pneumonitis. Cancer has spread to lymph nodes on the same side of the chest as the primary tumor and possibly the other side. The cancer may have spread to other lymph nodes above the collarbone. There may be one or more additional tumors in the same lobe of the lung as the primary tumor. Cancer may have spread to the chest wall, diaphragm, heart, trachea, esophagus, breastbone or backbone, major blood vessels of the heart, or additional areas.

Stage IV
In this stage, the tumor may be any size and the cancer may have spread to the lymph nodes. There may be one or more tumors in the lung that does not have the primary tumor. Cancer is found in the lining around the lungs or the sac around the heart and/or found in the fluid around the lungs or the heart. Cancer has spread to one or more organs that are not near the lungs, such as the brain, kidney, liver or adrenal gland. Cancer may have spread to bone or lymph nodes that are not near the lung.