Once the diagnosis is confirmed, the cancer is assigned a stage. The stages are determined by the size of the tumor (T), whether or not it has moved into the lymph nodes (N), and whether or not it has metastasized (spread to other sites; M). Staging is important for determining the treatment plan. In general, the lower the stage, the more favorable the prognosis (most likely outcome).
Non-small Cell Lung Cancer Staging
Non-small cell lung cancers are usually staged according to the TNM system, a classification developed and revised by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer (UICC; International Union Against Cancer). The system looks like this:
T = tumor size
N = node involvement
M = metastasis status
The primary tumor (T) is further classified as follows:
TX: The tumor cannot be evaluated, or it is proven by the presence of cancer cells in the sputum or bronchial washings, bronchial washings, but cannot be seen during imaging or bronchoscopy. This is also called an occult tumor.
T0: No evidence of a primary tumor.
Tis: Known as carcinoma in situ, the cancer is found only in the layer of cells lining the air passages.
T1: The tumor is 3 centimeters (cm) in diameter or less, has not spread to the membranes that surround the lung (visceral pleura), and is not in the main stem bronchus.
T2: One or more of the following features are present:
The tumor is larger than 3 cm and involves a main bronchus, but is not closer than 2 cm to the carina (the point where the windpipe branches into the left and right main bronchi).
ยท It has spread to the membranes surrounding the lung.
The lung has not collapsed or developed pneumonia, but the cancer partially clogs the airway.