After non-small cell 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.
In the occult (hidden) stage, cancer cells are found in sputum (mucus coughed up from the lungs), but no tumor can be found in the lung by imaging or bronchoscopy, or the primary tumor is too small to be checked.
In stage 0, abnormal cells are found in the innermost lining of the airways. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ (localized).
Cancer has formed. Stage I is divided into stages IA and IB:
Stage II is divided into stages IIA and IIB:
Stage III is divided into stages IIIA, IIIB, IIIC:
Stage IV is divided into stages IVA and IVB.