This is a medical question of type : stages 
 What are the stages of Non-Small Cell Lung Cancer ? 
 Key Points
                    - After lung cancer has been diagnosed, tests are done to find out if cancer cells have spread within the lungs or to other parts of the body.     - There are three ways that cancer spreads in the body.    - Cancer may spread from where it began to other parts of the body.    - The following stages are used for non-small cell lung cancer:         - Occult (hidden) stage     - Stage 0 (carcinoma in situ)     - Stage I     - Stage II     - Stage IIIA     - Stage IIIB     - Stage IV
                
                
                    After lung cancer has been diagnosed, tests are done to find out if cancer cells have spread within the lungs or to other parts of the body.
                    The process used to find out if cancer has spread within the lungs or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. Some of the tests used to diagnose non-small cell lung cancer are also used to stage the disease. (See the General Information section.)    Other tests and procedures that may be used in the staging process include the following:         -   MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the brain. This procedure is also called nuclear magnetic resonance imaging (NMRI).    -   CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the brain and abdomen, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.    -   PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.    -   Radionuclide bone scan : A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones and is detected by a scanner.     -   Pulmonary function test (PFT): A test to see how well the lungs are working. It measures how much air the lungs can hold and how quickly air moves into and out of the lungs. It also measures how much oxygen is used and how much carbon dioxide is given off during breathing. This is also called lung function test.    -   Endoscopic ultrasound (EUS): A procedure in which an endoscope is inserted into the body. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. A probe at the end of the endoscope is used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. This procedure is also called endosonography. EUS may be used to guide fine needle aspiration (FNA) biopsy of the lung, lymph nodes, or other areas.     -   Mediastinoscopy : A surgical procedure to look at the organs, tissues, and lymph nodes between the lungs for abnormal areas. An incision (cut) is made at the top of the breastbone and a mediastinoscope is inserted into the chest. A mediastinoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue or lymph node samples, which are checked under a microscope for signs of cancer.    -   Anterior mediastinotomy : A surgical procedure to look at the organs and tissues between the lungs and between the breastbone and heart for abnormal areas. An incision (cut) is made next to the breastbone and a mediastinoscope is inserted into the chest. A mediastinoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue or lymph node samples, which are checked under a microscope for signs of cancer. This is also called the Chamberlain procedure.    -  Lymph node biopsy : The removal of all or part of a lymph node. A pathologist views the tissue under a microscope to look for cancer cells.     -   Bone marrow aspiration and biopsy : The removal of bone marrow, blood, and a small piece of bone by inserting a hollow needle into the hipbone or breastbone. A pathologist views the bone marrow, blood, and bone under a microscope to look for signs of cancer.
                
                
                    There are three ways that cancer spreads in the body.
                    Cancer can spread through tissue, the lymph system, and the blood:         - Tissue. The cancer spreads from where it began by growing into nearby areas.     - Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.     - Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.
                
                
                    Cancer may spread from where it began to other parts of the body.
                    When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.         - Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.    - Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.        The metastatic tumor is the same type of cancer as the primary tumor. For example, if non-small cell lung cancer spreads to the brain, the cancer cells in the brain are actually lung cancer cells. The disease is metastatic lung cancer, not brain cancer.
                
                
                    The following stages are used for non-small cell lung cancer:
                    Occult (hidden) stage    In the occult (hidden) stage, cancer cannot be seen by imaging or bronchoscopy. Cancer cells are found in sputum (mucus coughed up from the lungs) or bronchial washing (a sample of cells taken from inside the airways that lead to the lung). Cancer may have spread to other parts of the body.       Stage 0 (carcinoma in situ)    In stage 0, abnormal cells are found in the lining of the airways. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.        Stage I     In stage I, cancer has formed. Stage I is divided into stages IA and IB:            -  Stage IA: The tumor is in the lung only and is 3 centimeters or smaller.     -  Stage IB: Cancer has not spread to the lymph nodes and one or more of the following is true:                  - The tumor is larger than 3 centimeters but not larger than 5 centimeters.       - Cancer has spread to the main bronchus and is at least 2 centimeters below where the trachea joins the bronchus.       - Cancer has spread to the innermost layer of the membrane that covers the lung.       - Part of the lung has collapsed or developed pneumonitis (inflammation of the lung) in the area where the trachea joins the bronchus.                          Stage II    Stage II is divided into stages IIA and IIB. Stage IIA and IIB are each divided into two sections depending on the size of the tumor, where the tumor is found, and whether there is cancer in the lymph nodes.            -  Stage IIA:  (1) Cancer has spread to lymph nodes on the same side of the chest as the tumor. The lymph nodes with cancer are within the lung or near the bronchus. Also, one or more of the following is true:                  - The tumor is not larger than 5 centimeters.       -  Cancer has spread to the main bronchus and is at least 2 centimeters below where the trachea joins the bronchus.       -  Cancer has spread to the innermost layer of the membrane that covers the lung.       - Part of the lung has collapsed or developed pneumonitis (inflammation of the lung) in the area where the trachea joins the bronchus.            or  (2) Cancer has not spread to lymph nodes and one or more of the following is true:                  - The tumor is larger than 5 centimeters but not larger than 7 centimeters.       - Cancer has spread to the main bronchus and is at least 2 centimeters below where the trachea joins the bronchus.       - Cancer has spread to the innermost layer of the membrane that covers the lung.       - Part of the lung has collapsed or developed pneumonitis (inflammation of the lung) in the area where the trachea joins the bronchus.                -  Stage IIB:  (1) Cancer has spread to nearby lymph nodes on the same side of the chest as the tumor. The lymph nodes with cancer are within the lung or near the bronchus. Also, one or more of the following is true:                  - The tumor is larger than 5 centimeters but not larger than 7 centimeters.       - Cancer has spread to the main bronchus and is at least 2 centimeters below where the trachea joins the bronchus.       -  Cancer has spread to the innermost layer of the membrane that covers the lung.       - Part of the lung has collapsed or developed pneumonitis (inflammation of the lung) in the area where the trachea joins the bronchus.             or (2) Cancer has not spread to lymph nodes and one or more of the following is true:                  - The tumor is larger than 7 centimeters.       - Cancer has spread to the main bronchus (and is less than 2 centimeters below where the trachea joins the bronchus), the chest wall, the diaphragm, or the nerve that controls the diaphragm.        - Cancer has spread to the membrane around the heart or lining the chest wall.       - The whole lung has collapsed or developed pneumonitis (inflammation of the lung).       - There are one or more separate tumors in the same lobe of the lung.                         Stage IIIA     Stage IIIA is divided into three sections depending on the size of the tumor, where the tumor is found, and which lymph nodes have cancer (if any).     (1) Cancer has spread to lymph nodes on the same side of the chest as the tumor. The lymph nodes with cancer are near the sternum (chest bone) or where the bronchus enters the lung. Also:            - The tumor may be any size.     - Part of the lung (where the trachea joins the bronchus) or the whole lung may have collapsed or developed pneumonitis (inflammation of the lung).     - There may be one or more separate tumors in the same lobe of the lung.     - 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.       - Membrane around the heart.                        or       (2) Cancer has spread to lymph nodes on the same side of the chest as the tumor. The lymph nodes with cancer are within the lung or near the bronchus. Also:            - The tumor may be any size.     - The whole lung may have collapsed or developed pneumonitis (inflammation of the lung).     - There may be one or more separate tumors in any of the lobes of the lung with cancer.     - 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.       - Major blood vessels that lead to or from the heart.        - Trachea.       -  Esophagus.        - Nerve that controls the larynx (voice box).       -  Sternum (chest bone) or backbone.       -  Carina (where the trachea joins the bronchi).                        or       (3) Cancer has not spread to the lymph nodes and the tumor may be any size. Cancer has spread to any of the following:            - Heart.      - Major blood vessels that lead to or from the heart.      - Trachea.      - Esophagus.      - Nerve that controls the larynx (voice box).     - Sternum (chest bone) or backbone.      - Carina (where the trachea joins the bronchi).              Stage IIIB     Stage IIIB is divided into two sections depending on the size of the tumor, where the tumor is found, and which lymph nodes have cancer.     (1) Cancer has spread to lymph nodes above the collarbone or to lymph nodes on the opposite side of the chest as the tumor. Also:            - The tumor may be any size.     - Part of the lung (where the trachea joins the bronchus) or the whole lung may have collapsed or developed pneumonitis (inflammation of the lung).     - There may be one or more separate tumors in any of the lobes of the lung with cancer.     - Cancer may have spread to any of the following:                  - Main 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.       - Major blood vessels that lead to or from the heart.       - Trachea.       -  Esophagus.       - Nerve that controls the larynx (voice box).       -  Sternum (chest bone) or backbone.       -  Carina (where the trachea joins the bronchi).                         or       (2) Cancer has spread to lymph nodes on the same side of the chest as the tumor. The lymph nodes with cancer are near the sternum (chest bone) or where the bronchus enters the lung. Also:            - The tumor may be any size.     - There may be separate tumors in different lobes of the same lung.     - Cancer has spread to any of the following:                  - Heart.        - Major blood vessels that lead to or from the heart.        - Trachea.        - Esophagus.       - Nerve that controls the larynx (voice box).       - Sternum (chest bone) or backbone.        - Carina (where the trachea joins the bronchi).                         Stage IV     In stage IV, the tumor may be any size and cancer may have spread to lymph nodes. One or more of the following is true:            - There are one or more tumors in both lungs.     - Cancer is found in fluid around the lungs or the heart.     - Cancer has spread to other parts of the body, such as the brain, liver, adrenal glands, kidneys, or bone.