Once lung cancer is diagnosed and the type of lung cancer is identified, doctors need to measure  if and/or by how much
the cancer has spread within the body. This is called "staging" and is usually determined during some of the investigation tests used to diagnose lung cancer. Staging of the lung cancer is required before the doctor can recommend
the type of treatment best suited to an individual patient.

There are different staging systems for each of the two main types of lung cancer.

Staging system: small cell lung cancer:

• Limited stage: the cancer is detected in only one lung and the surrounding lymph nodes.
• Extensive disease: used to classify lung cancer that has progressed further than limited stage disease.

Staging system: Non-small cell lung cancer (NSCLC):

Stage 0: Cancer cells are found only in the original tumour within the lung.

Stage I: Cancer cells are limited to the lung.

Stage II: Cancer has spread to nearby lymph nodes, or a tumour which has grown into the chest wall, lining of the lungs or the outer lining that surrounds the heart.

Stage III: Cancer has spread to the lymph nodes in the centre of the chest between the heart and lungs (the mediastinum). Blood vessles in this area may also be affected. Or, cancer has spread to the opposite side of the chest from which the cancer was originally detected.

Stage IV: The cancer cells have spread beyond the chest area to other parts of the body (such as the bones, liver and kidneys).