Staging is the process of finding out how far a cancer has spread. Your treatment and prognosis (outlook) depend, to a large extent, on the cancer's stage. There are actually 2 types of staging.

The clinical stage is based on the results of the physical exam, biopsies, and imaging tests (CT scan, chest x-ray, PET scan, etc.), which are described in the section "How is small cell lung cancer diagnosed?"

If you have surgery, your doctor can also determine a pathologic stage, which is based on the same factors as the clinical stage, plus what is found as a result of the surgery.

The clinical and pathologic stages may be different in some cases. For example, during surgery the doctor may find cancer in an area that did not show up on imaging tests, which might give the cancer a more advanced pathologic stage.

Because most patients with lung cancer do not have surgery, the clinical stage is most often used when describing the extent of this cancer. However, when it is available, the pathologic stage is likely to be more accurate than the clinical stage, as it is based on your doctor's firsthand impression of the extent of your disease.

A staging system is a standard way for the cancer care team to summarize how large a cancer is and how far it has spread. There are 2 staging systems that can be used to describe the extent of spread of small cell lung cancer (SCLC).

Limited and extensive stage

For treatment purposes, most doctors prefer the 2-stage system that divides small cell lung cancers into limited stage and extensive stage.

Limited stage usually means that the cancer is only in one lung and perhaps lymph nodes on the same side of the chest. The cancer is typically confined to an area that is small enough to be treated with radiation therapy.

Spread of the cancer to the other lung, to lymph nodes on the other side of the chest, or to distant organs indicates extensive disease. Many doctors consider small cell lung cancer that has spread to the fluid around the lung to be extensive stage as well. About 2 out of 3 people with small cell lung cancer have extensive disease when their cancer is first found.

Small cell lung cancer is often staged in this way because it helps separate patients who may be able to get local treatments such as surgery and/or radiation therapy to try to cure the cancer (limited stage) from those who are very unlikely to be cured (extensive stage).

The TNM staging system

A more formal system to describe the growth and spread of lung cancer is the American Joint Committee on Cancer (AJCC) TNM staging system. This system is used more often for non-small cell lung cancer. It is used less often for SCLC, mainly because treatment options and outlook don't vary much between these detailed stages. The TNM system describes 3 key pieces of information:

• 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. Lymph nodes are small bean-shaped collections of immune system cells that help fight infections. Cancers often spread to the lymph nodes before going to other parts of the body.

• M indicates whether the cancer has spread (metastasized) to other organs of the body. (The most common sites are the liver, bones, and brain.)

Numbers or letters appear after T, N, and M to provide more details about each of these factors. The numbers 0 through 4 indicate increasing severity. The letter X means "cannot be assessed because the information is not available."

T categories for 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 top layers of cells lining the air passages. It has not grown into deeper lung tissues. This stage is also known as carcinoma in situ.

T1: The tumor is no larger than 3 centimeters (slightly less than 1¼ inches) 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 1 or more of the following features:

• It is larger than 3 centimeters (cm) across.

• It involves a main bronchus, but is not closer than 2 cm (about ¾ inch) to the carina (the point where the windpipe splits into the left and right main bronchi).

• It has grown into the membranes that surround the lungs (visceral pleura).

• The tumor partially clogs the airways, but this has not caused the entire lung to collapse or develop pneumonia.

T3: The tumor can be any size and has 1 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 2 cm (about ¾ inch) 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.

T4: The cancer has 1 or more of the following features:

• A tumor of any size has grown into the space behind the chest bone and in front of the heart (mediastinum), the heart, the large blood vessels near the heart (such as the aorta), the windpipe, the esophagus (tube connecting the throat to the stomach), the backbone, or the carina.

• 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).

N categories for 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). Affected lymph nodes are on the same side as the primary tumor(s).

N2: Spread to lymph nodes around the carina (the point where the windpipe splits into the left and right bronchi) 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.

N3: Spread to lymph nodes near the collarbone on either side, and/or spread to hilar or mediastinal lymph nodes on the side opposite the primary tumor.

M categories for lung cancer

MX: Spread to distant areas cannot be assessed.

M0: No spread to distant organs or areas. This includes other lobes of the lungs, lymph nodes further away than those mentioned in the N stages above, and other organs or tissues such as the liver, bones, or brain.

M1: The cancer has spread to 1 or more distant sites. This can be to another lobe of the lung, to distant lymph nodes, or to other organs.

Stage grouping

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 cancers that have a similar prognosis. Patients with lower stage numbers tend to have a better prognosis. Again, these stages are more likely to be useful for non-small cell lung cancer than for small cell lung cancer.

Occult cancer

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

Stage 0

Tis, N0, M0: The cancer is found only in the top layers of cells lining the air passages. It has not invaded deeper into other lung tissues and has not spread to lymph nodes or distant sites.

Stage IA

T1, N0, M0: The cancer is no larger than 3 centimeters (slightly less than 1¼ inches) 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 1 or more of the following features:

• The main tumor is larger than 3 cm across.
• The tumor involves a main bronchus, but is not within 2 cm of the carina.
• The tumor has grown into the visceral pleura (the membranes surrounding the lungs).
• The cancer is partially clogging the airways.

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

Stage IIA

T1, N1, M0: The cancer is no larger than 3 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 2 combinations of categories that make up this stage.

T2, N1, M0: The cancer has 1 or more of the following features:

• The main tumor is larger than 3 cm across.
• The tumor involves a main bronchus, but is not within 2 cm of the carina.
• The tumor has grown into the visceral pleura (the membranes surrounding the lungs).
• The cancer is partially clogging 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 1 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 lungs (mediastinal pleura), or membranes of the sac surrounding the heart (parietal pericardium).

• It invades a main bronchus and is closer than 2 cm (about ¾ inch) 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 4 main combinations of categories that make up this stage.

T1, N2, M0: The cancer is no larger than 3 cm, 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 (the point where the windpipe splits into the left and right bronchi) 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 1 or more of the following features:

• The main tumor is larger than 3 cm across.
• The tumor involves a main bronchus, but is not within 2 cm of the carina.
• The tumor has grown into the visceral pleura (the membranes surrounding the lungs).
• The cancer is partially clogging the airways.

The cancer has also spread to lymph nodes around the carina (the point where the windpipe splits into the left and right bronchi) 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 1 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 lungs (mediastinal pleura), or membranes of the sac surrounding the heart (parietal pericardium).

• It invades a main bronchus and is closer than 2 cm 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 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 1 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 2 cm 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 (the point where the windpipe splits into the left and right bronchi) 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 2 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 side opposite the primary tumor. The cancer has not spread to distant sites.

T4, any N, M0: The cancer has 1 or more of the following features:

• A tumor of any size has grown into the space behind the chest bone and in front of the heart (mediastinum), the heart, the large blood vessels near the heart (such as the aorta), the windpipe, the esophagus (tube connecting the throat to the stomach), the backbone, or the carina.

• 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.

Again, the TNM staging system isn't used often for small cell lung cancer

Survival rates for small cell lung cancer by stage

Survival rates are a way for doctors and patients to get a general idea of the outlook for people with a certain type and stage of cancer. Some people want to know the statistics for people in their situation, while others may not find them helpful, or may even not want to know them. Whether or not you want to read about the survival statistics below for small cell lung cancer is up to you.

The numbers below are relative survival rates calculated from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database, based on people who were diagnosed with small cell lung cancer between 1988 and 2001. There are some important points to note about these numbers:

• The 5-year survival rate refers to the percentage of patients who live at least 5 years after being diagnosed. Many of these patients live much longer than 5 years after diagnosis. Five-year relative survival rates (such as the numbers below) adjust for patients who die from causes other than lung cancer. They are considered to be a more accurate way to describe the outlook for patients with a particular type and stage of cancer.

• These numbers were derived from patients treated at least several years ago. These are the most current numbers we have available, but improvements in treatment since then mean that the survival rates for people now being diagnosed with these cancers may be higher.

• Survival statistics can sometimes be useful as a general guide, but they may not accurately represent any one person's prognosis. A number of other factors, including other tumor characteristics and a person's age and general health, can also affect outlook. Your doctor is likely to be a good source as to whether these numbers may apply to you, as he or she is familiar with the aspects of your particular situation.

Last Medical Review: 10/13/2009
Last Revised: 10/13/2009