T3: One or more of the following features are present:
The tumor of any size has directly invaded the chest wall, diaphragm (breathing muscle that separates the chest from the abdomen), the mediastinal pleura (the membranes surrounding the space between the two lungs), or the parietal pericardium (membranes of the sac surrounding the heart).
The cancer has invaded a main bronchial tube and is closer than 2 cm to the point where the windpipe branches into the both bronchi, but does not affect this area.
The tumor has moved enough into the airways to cause the collapse of a lung or pneumonia in the entire lung.
T4: One or more of the following features are present:
A tumor that that has invaded the heart, great vessels (aorta, superior or inferior vena cava, pulmonary artery, or pulmonary vein), trachea (windpipe), esophagus (tube connecting the throat to the stomach), backbone, or the carina (the point where the windpipe branches into the bronchial tubes).
ยท Two or more separate tumor nodules are present in the same lobe.
There is a fluid containing cancer cells in the space surrounding the lung (malignant pleural effusion).
The Node Involvement (N) is further classified as follows:
NX: The regional lymph nodes cannot be assessed.
N0: No spread to lymph nodes.
N1: The cancer has spread to lymph nodes within the lung and/or located around the area where the bronchus enters the lung (hilar lymph nodes), but only affects lymph nodes on the same side as the cancerous lung.
N2: The lymph nodes around the point where the windpipe branches into the bronchial tubes or the mediastinum (behind the chest bone and in front of the heart) has been invaded by the cancerous cells. The affected lymph nodes are on the same side of the cancerous lung.
N3: The cancer has spread to lymph nodes near the collarbone on either side, to hilar or mediastinal lymph nodes on the side opposite the cancerous lung.
The Metastasis Status (M) is classified as follows:
MX: Distant metastasis cannot be assessed.
M0: No spread to distant organs. Sites considered distant areas include other lobes of the lungs, lymph nodes beyond the ones in the N stages, and other organs or tissues such as the liver, bones, brain, etc.
M1: The cancer has spread to distant organs.
These classifications are combined (stage grouping) and then an overall stage is assigned. Those stages are as follows: