Lung Cancer Staging Systems

Just as other asbestos-related diseases are often diagnosed in late stages of development, asbestos-induced lung cancer may not produce symptoms until the disease has reached a late stage of development. This unfortunate fact can end up complicating the treatment options available to asbestos-related lung cancer patients.

To plan the best treatment, a doctor needs to know the type of lung cancer and the extent (stage) of the disease. Staging is a careful attempt to find out whether the cancer has spread, and if so, to what parts of the body.

TNM is a system used to describe the growth and spread of non-small cell lung cancer (NSCLC). TNM entails three key pieces of information:

The TNM Staging System

• T indicates the size of the main (primary) tumor and whether it has grown into nearby areas.
• N describes how much the cancer has spread to nearby (regional) lymph nodes.
• M indicates whether the cancer has spread (metastasized) to other organs of the body. The most common sites are the liver, bones, and brain.

Medical professionals use numbers or letters after T, N, and M to provide more details about each of these factors. Numbers zero through four indicate increasing severity. The letter X means the symptom cannot be assessed because the information is not available.

T Categories for Non-Small Cell Lung Cancer

TX: Main (primary) tumor can't be assessed, or cancer cells were seen on sputum cytology, but no tumor can be found.
T0: No evidence of a primary tumor.
Tis: Cancer is found only in the layer of cells lining the air passages. This stage is also known as carcinoma in situ.
T1: The tumor is no larger than three centimeters across, has not reached the membranes that surround the lungs (visceral pleura), and does not affect the main branches of the bronchi.
T2: The tumor has one or more of the following features:

• It is larger than three centimeters across
• It involves a main bronchus, but is not closer than two cm to the carina
• It has extended into the membranes that surround the lungs (visceral pleura)
• The tumor partially blocks the airways

T3: The tumor has one or more of the following features:

• A tumor of any size has grown into areas such as the chest wall, diaphragm, mediastinal pleura, or parietal pericardium.
• It invades a main bronchus and is closer than two cm to the carina, but does not extend into the carina itself.
• It has grown into the airways enough to cause an entire lung to collapse or to cause pneumonia in the entire lung.

T4: The tumor has one or more of the following features:

• Invasion of the mediastinal organs, which include the esophagus, carina, large blood vessels, and/ or heart.
• Two or more separate tumor nodules are present in the same lobe of a lung.
• There is a fluid containing cancer cells in the space surrounding the lung (malignant pleural effusion).

N Categories for Non-Small Cell Lung Cancer

NX: Nearby lymph nodes cannot be assessed.
N0: No spread to nearby lymph nodes.
N1: Spread to lymph nodes within the lung and/or around the area where the bronchus enters the lung (hilar lymph nodes).
N2: Spread to lymph nodes around the carina or in the space behind the breastbone and in front of the heart (mediastinum).
N3: Spread to lymph nodes near the collarbone on either side, and/or spread to hilar or mediastinal lymph nodes.
M Categories for Non-Small Cell Lung Cancer
M0: No spread to distant organs or areas.
M1: Spread to one or more distant sites.

Once the T, N, and M categories have been assigned, this information is combined (stage grouping) to assign an overall stage of 0, I, II, III, or IV. Some stages are subdivided into A and B. The stages identify tumor types that have a similar prognosis and thus are treated in a similar way. Patients with lower stage numbers tend to have a better prognosis.

Occult Cancer

TX, N0, M0: Cancer cells are seen in a sample of sputum or other lung fluids, but the location of the cancer cannot be determined.

Stage 0
Tis, N0, M0: The cancer is found only in the layer of cells lining the air passages.

Stage IA
T1, N0, M0: The cancer is no larger than three centimeters across, has not reached the membranes that surround the lungs, and does not affect the main branches of the bronchi. It has not spread to lymph nodes or distant sites.

Stage IB
T2, N0, M0: The cancer has one or more of the following features:

• The main tumor is larger than three centimeters across.
• The tumor involves a main bronchus, but is not within two centimeters of the carina.
• The tumor has grown into the visceral pleura (the membranes surrounding the lungs).
• The cancer is partially blocking the airways.

The cancer has not spread to lymph nodes or distant sites.

Stage IIA

T1, N1, M0: The cancer is no larger than three centimeters, has not grown into the membranes that surround the lungs, and does not affect the main branches of the bronchi. It has spread to lymph nodes within the lung and/or around the area where the bronchus enters the lung (hilar lymph nodes). It has not spread to distant sites.

Stage IIB

There are two combinations of categories that make up this stage.

T2, N1, M0: The cancer has one or more of the following features:

• The main tumor is larger than three centimeters across.
• The tumor involves a main bronchus, but is not within two centimeters of the carina.
• The tumor has grown into the visceral pleura (the membranes surrounding the lungs).
• The cancer is partially blocking the airways.

It has also spread to lymph nodes within the lung and/or around the area where the bronchus enters the lung (hilar lymph nodes). It has not spread to distant sites.

T3, N0, M0: The main tumor can be any size and has one or more of the following features:

• It has grown into the chest wall, the breathing muscle that separates the chest from the abdomen (diaphragm), the membranes surrounding the space between the two lungs (mediastinal pleura), or membranes of the sac surrounding the heart (parietal pericardium).
• It invades a main bronchus and is closer than two centimeters to the carina, but it does not involve the carina itself.
• It has grown into the airways enough to cause an entire lung to collapse or to cause pneumonia in the entire lung.

The cancer has not spread to lymph nodes or distant sites.

Stage IIIA

There are four main combinations of categories that make up this stage.

T1, N2, M0: The cancer is no larger than three centimeters, has not grown into the membranes that surround the lungs, and does not affect the main branches of the bronchi. The cancer has spread to lymph nodes around the carina or in the space behind the breastbone, and in front of the heart (mediastinum). Affected lymph nodes are on the same side as the primary tumor. The cancer has not spread to distant sites.

T2, N2, M0: The cancer has one or more of the following features:

• The main tumor is larger than three centimeters across.
• The tumor involves a main bronchus, but is not within two centimeters of the carina.
• The tumor has grown into the visceral pleura (the membranes surrounding the lungs).
• The cancer is partially blocking the airways.

The cancer has also spread to lymph nodes around the carina or in the space behind the breastbone, and in front of the heart (mediastinum). Affected lymph nodes are on the same side as the primary tumor. The cancer has not spread to distant sites.

T3, N1, M0: The tumor can be any size and has one or more of the following features:

• It has grown into the chest wall, the breathing muscle that separates the chest from the abdomen (diaphragm), the membranes surrounding the space between the two lungs (mediastinal pleura), or membranes of the sac surrounding the heart (parietal pericardium).
• It invades a main bronchus and is closer than two centimeters to the carina, but it does not involve the carina itself.
• It has grown into the airways enough to cause an entire lung to collapse or to cause pneumonia in the entire lung.

It has also spread to lymph nodes within the lung and/or around the area where the bronchus enters the lung (hilar lymph nodes). It has not spread to distant sites.

T3, N2, M0: The tumor can be any size and has one or more of the following features:

• It has grown into the chest wall, the breathing muscle that separates the chest from the abdomen (diaphragm), the membranes surrounding the space between the two lungs (mediastinal pleura), or membranes of the sac surrounding the heart (parietal pericardium).
• It invades a main bronchus and is closer than two centimeters to the carina, but it does not involve the carina itself.
• It has grown into the airways enough to cause an entire lung to collapse or to cause pneumonia in the entire lung.

The cancer has also spread to lymph nodes around the carina or in the space behind the breastbone, and in front of the heart (mediastinum). Affected lymph nodes are on the same side as the primary tumor. The cancer has not spread to distant sites.

Stage IIIB

There are two combinations of categories that make up this stage.

Any T, N3, M0: The cancer can be of any size. It may or may not have grown into nearby structures or caused pneumonia or lung collapse. It has spread to lymph nodes near the collarbone on either side, and/or has spread to hilar or mediastinal lymph nodes on the opposite side of the primary tumor. The cancer has not spread to distant sites.

T4, any N, M0: The cancer has one or more of the following features:

• A tumor of any size has grown into the mediastinum, heart, windpipe, esophagus, backbone, carina, or the large vessels near the heart.
• Two or more separate tumor nodules are present in the same lobe of a lung.
• There is a fluid containing cancer cells in the space surrounding the lung (a malignant pleural effusion).

The cancer may or may not have spread to nearby lymph nodes. It has not spread to distant sites.

Stage IV

Any T, Any N, M1: The cancer can be any size and may or may not have grown into nearby structures or reached nearby lymph nodes. It has spread to distant sites.

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