Lung Cancer (Small Cell)

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Early Detection, Diagnosis, and Staging TOPICS

How is small cell lung cancer staged?

The stage of a cancer describes how far it has spread. Your treatment and prognosis (outlook) depend, to a large extent, on the cancer’s stage.

There are actually 2 types of staging for small cell lung cancer (SCLC).

  • 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 SCLC 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 uses the additional information obtained at surgery.

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 SCLC.

Limited and extensive stage

For treatment purposes, most doctors use a 2-stage system that divides SCLC into limited stage and extensive stage.

Limited stage means that the cancer is only in one side of the chest and can be treated with a single radiation field. This can include one lung (unless tumors are widespread throughout the lung), as well as the lymph nodes on the same side of the chest. Lymph nodes above the collarbone (clavicle) can be affected in limited stage as long as they are on the same side of the chest as the cancer. Some doctors also include lymph nodes at the center of the chest (mediastinal lymph nodes) even when they are closer to the other side of the chest. What is important is that the cancer is confined to an area that is small enough to be treated with radiation therapy in one “port.” In only about 1 out of 3 people with SCLC is the cancer limited stage when it is first found.

Extensive stage is used to describe cancers that have spread widely throughout the lung, to the other lung, to lymph nodes on the other side of the chest, or to distant organs (including the bone marrow). Many doctors consider SCLC that has spread to the fluid around the lung to be extensive stage as well. About 2 out of 3 people with SCLC have extensive disease when their cancer is first found.

SCLC is often staged in this way because it helps doctors decide if a patient might benefit from more aggressive treatments such as chemotherapy combined with radiation therapy to try to cure the cancer (limited stage), or whether chemotherapy alone is likely to be a better option (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. The TNM system is based on 3 key pieces of information:

  • T indicates the size of the main (primary) tumor and whether it has grown into nearby areas.
  • N describes the spread of cancer to nearby (regional) lymph nodes. Lymph nodes are small bean-shaped collections of immune system cells to which cancers often spread 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 brain, bones, adrenal glands, liver, kidneys, and the other lung.)

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 TNM staging system is complex and can be hard for patients (and even some doctors) to understand. If you have any questions about the stage of your cancer, ask your doctor to explain it to you.

T categories for lung cancer

TX: The main (primary) tumor can’t be assessed, or cancer cells were seen on sputum cytology or bronchial washing but no tumor can be found.

T0: There is 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 is also known as carcinoma in situ.

T1: The tumor is no larger than 3 centimeters (cm)—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.

If the tumor is 2 cm (about 4/5 of an inch) or less across, it is called T1a. If the tumor is larger than 2 cm but not larger than 3 cm across, it is called T1b.

T2: The tumor has 1 or more of the following features:

  • It is larger than 3 cm across but not larger than 7 cm.
  • 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.

If the tumor is 5 cm or less across, it is called T2a. If the tumor is larger than 5 cm across (but not larger than 7 cm), it is called T2b.

T3: The tumor has 1 or more of the following features:

  • It is larger than 7 cm across.
  • 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.
  • Two or more separate tumor nodules are present in the same lobe of a lung

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

  • A tumor of any size has grown into the space between the lungs (mediastinum), the heart, the large blood vessels near the heart (such as the aorta), the windpipe (trachea), the tube connecting the throat to the stomach (esophagus), the backbone, or the carina.
  • Two or more separate tumor nodules are present in different lobes of the same lung.

N categories for lung cancer

NX: Nearby lymph nodes cannot be assessed.

N0: There is no spread to nearby lymph nodes.

N1: The cancer has 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.

N2: 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 between the lungs (mediastinum). Affected lymph nodes are on the same side as the primary tumor.

N3: The cancer has 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

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

M1a: Any of the following:

  • The cancer has spread to the other lung
  • Cancer cells are found in the fluid around the lung (called a malignant pleural effusion)
  • Cancer cells are found in the fluid around the heart (called a malignant pericardial effusion)

M1b: The cancer has spread to distant lymph nodes or to other organs such as the liver, bones, or brain.

Stage grouping for lung cancer

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

Occult (hidden) cancer

TX, N0, M0: Cancer cells are seen in a sample of sputum or other lung fluids, but the cancer isn’t found with other tests, so its location 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

T1a/T1b, N0, M0: The cancer is no larger than 3 cm 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

T2a, N0, M0: The cancer has 1 or more of the following features:

  • The main tumor is between larger than 3 cm across but not larger than 5 cm.
  • The tumor has grown into a main bronchus, but is not within 2 cm of the carina (and it is not larger than 5 cm).
  • The tumor has grown into the visceral pleura (the membranes surrounding the lungs) and is not larger than 5 cm.
  • The tumor is partially clogging the airways (and is not larger than 5 cm).

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

Stage IIA

There are 3 main combinations of categories that make up this stage.

T1a/T1b, N1, M0: The cancer is no larger than 3 cm across, 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). These lymph nodes are on the same side as the cancer. It has not spread to distant sites.

OR

T2a, N1, M0: The cancer has 1 or more of the following features:

  • The main tumor is larger than 3 cm across but not larger than 5 cm.
  • The tumor has grown into a main bronchus, but is not within 2 cm of the carina (and it is not larger than 5 cm).
  • The tumor has grown into the visceral pleura (the membranes surrounding the lungs) and is not larger than 5 cm.
  • The tumor is partially clogging the airways (and is not larger than 5 cm).

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). These lymph nodes are on the same side as the cancer. It has not spread to distant sites.

OR

T2b, N0, M0: The cancer has 1 or more of the following features:

  • The main tumor is larger than 5 cm across but not larger than 7 cm.
  • The tumor has grown into a main bronchus, but is not within 2 cm of the carina (and it is between 5 and 7 cm across).
  • The tumor has grown into the visceral pleura (the membranes surrounding the lungs) and is between 5 and 7 cm across.
  • The tumor is partially clogging the airways (and is between 5 and 7 cm across).

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

Stage IIB

There are 2 combinations of categories that make up this stage.

T2b, N1, M0: The cancer has 1 or more of the following features:

  • The main tumor is larger than 5 cm across but not larger than 7 cm.
  • The tumor has grown into a main bronchus, but is not within 2 cm of the carina (and it is between 5 and 7 cm across).
  • The tumor has grown into the visceral pleura (the membranes surrounding the lungs) and is between 5 and 7 cm across.
  • The cancer is partially clogging the airways (and is between 5 and 7 cm across).

It has also spread to lymph nodes within the lung and/or around the area where the bronchus enters the lung (hilar lymph nodes). These lymph nodes are on the same side as the cancer. It has not spread to distant sites.

OR

T3, N0, M0: The main tumor has 1 or more of the following features:

  • It is larger than 7 cm across.
  • 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.
  • Two or more separate tumor nodules are present in the same lobe of a lung.

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

Stage IIIA

There are 3 main combinations of categories that make up this stage.

T1 to T3, N2, M0: The main tumor can be any size. It has not grown into the space between the lungs (mediastinum), the heart, the large blood vessels near the heart (such as the aorta), the windpipe (trachea), the tube connecting the throat to the stomach (esophagus), the backbone, or the carina. It has not spread to different lobes of the same lung.

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 between the lungs (mediastinum). These lymph nodes are on the same side as the main lung tumor. The cancer has not spread to distant sites.

OR

T3, N1, M0: The cancer has 1 or more of the following features:

  • It is larger than 7 cm across.
  • 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.
  • Two or more separate tumor nodules are present in the same lobe of a lung
  • 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). These lymph nodes are on the same side as the cancer. It has not spread to distant sites.

OR

T4, N0 or N1, M0: The cancer has 1 or more of the following features:

  • A tumor of any size has grown into the space between the lungs (mediastinum), the heart, the large blood vessels near the heart (such as the aorta), the windpipe (trachea), the tube connecting the throat to the stomach (esophagus), the backbone, or the carina.
  • Two or more separate tumor nodules are present in different lobes of the same lung.

It may or may not have spread to lymph nodes within the lung and/or around the area where the bronchus enters the lung (hilar lymph nodes). Any affected lymph nodes are on the same side as the cancer. It 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.

OR

T4, N2, M0: The cancer has 1 or more of the following features:

  • A tumor of any size has grown into the space between the lungs (mediastinum), the heart, the large blood vessels near the heart (such as the aorta), the windpipe (trachea), the tube connecting the throat to the stomach (esophagus), the backbone, or the carina.
  • Two or more separate tumor nodules are present in different lobes of the same 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 between the lungs (mediastinum). Affected lymph nodes are on the same side as the main lung tumor. It has not spread to distant sites.

Stage IV

There are 2 combinations of categories that make up this stage.

Any T, any N, M1a: The cancer can be any size and may or may not have grown into nearby structures or reached nearby lymph nodes. In addition, any of the following is true:

  • The cancer has spread to the other lung
  • Cancer cells are found in the fluid around the lung (called a malignant pleural effusion)
  • Cancer cells are found in the fluid around the heart (called a malignant pericardial effusion)

OR

Any T, any N, M1b: 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 lymph nodes or to other organs such as the liver, bones, or brain.


Last Medical Review: 09/12/2014
Last Revised: 11/10/2014