Staging

Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer's stage, so staging may not be complete until all the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis (chance of recovery). There are different stage descriptions for different types of cancers.

One tool that doctors use to describe the stage is the TNM system. This system uses three criteria to judge the stage of the cancer: the tumor itself, the lymph nodes around the tumor, and if the tumor has spread to the rest of the body. The results are combined to determine the stage of cancer for each person. There are five stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer so doctors can work together to plan the best treatments.

TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:

• How large is the primary tumor and where is it located? (Tumor, T)
  
  
• Has the tumor spread to the lymph nodes? (Node, N)
  
  
• Has the cancer metastasized (spread) to other parts of the body? (Metastasis, M)

Tumor. Using the TNM system, the "T" plus a letter and/or number (0 to 4) is used to describe the stage of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. This helps the doctor develop the best treatment plan for each patient. Specific tumor stage information is listed below:

TX: The primary tumor cannot be evaluated.

T0: There is no tumor.

T1: The tumor invades the ipsilateral parietal pleura (the thin membrane that lines the inner chest walls on the same side of the body as the tumor), with or without involvement of the visceral pleura (the innermost of the two layers of the pleura).

T1a: The tumor invades the ipsilateral parietal pleura, with no involvement of the visceral pleura.

T1b: The tumor invades the ipsilateral parietal pleura, with involvement of the visceral pleura.

T2: The tumor invades any of the ipsilateral pleural surfaces with at least one of the following: visceral pleural tumor, invasion of the diaphragmatic muscle (the muscle that separates the chest cavity from the abdomen), or invasion of the lung.

T3: The tumor involves any of the ipsilateral pleural surfaces, with at least one of the following: invasion of the endothoracic fascia (the membrane that surrounds the thorax) and/or invasion into mediastinal fat.

T4: The tumor involves any of the ipsilateral pleural surfaces, with at least one of the following: diffuse or multifocal invasion of soft tissues of the chest wall, any involvement of rib, invasion through the diaphragm to the peritoneum, invasion of any mediastinal organ(s), direct extension to the contralateral pleura, invasion into the spine, extension to the internal surface of the pericardium, pericardial effusion with positive cytology, invasion of the myocardium, and/or invasion of the brachial plexus.

Node. The “N” in the TNM staging system stands for lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes near the chest are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes.

NX: The regional lymph nodes cannot be assessed.

N0 (N plus zero): There is no regional lymph node metastasis.

N1: There is metastasis to the ipsilateral bronchopulmonary and/or hilar lymph node(s).

N2: There is metastasis to the subcarinal lymph node(s) and/or the ipsilateral internal mammary or mediastinal lymph node(s).

N3: There is metastasis to the contralateral mediastinal, internal mammary, or hilar lymph node(s) and/or the ipsilateral or contralateral supraclavicular or scalene lymph node(s).

Distant metastasis. The “M” in the TNM system indicates whether the cancer has spread to other parts of the body.

MX: Distant metastasis cannot be evaluated.

M0 (M plus zero): There is no distant metastasis.

M1: There is metastasis to other parts of the body.

Cancer stage grouping

Doctors assign the stage of the cancer by combining the T, N, and M classifications.

Stage I: The tumor has invaded the ipsilateral parietal pleura, with or without involvement of the visceral pleura, but has not spread to the lymph nodes or other parts of the body (T1, N0, M0).

Stage IA: The tumor has invaded the ipsilateral parietal pleura, without involvement of the visceral pleura, but has not spread to the lymph nodes or other parts of the body (T1a, N0, M0).

Stage IB: The tumor has invaded the ipsilateral parietal pleura, with involvement of the visceral pleura, but has not spread to the lymph nodes or other parts of the body (T2a, N0, M0).

Stage II: The tumor has invaded any of the ipsilateral pleural surfaces with at least one of the following: visceral pleural tumor, invasion of the diaphragmatic muscle, or invasion of the lung. The cancer has not spread to the lymph nodes or throughout the body (T2, N0, M0).

Stage III: The cancer has invaded any of the ipsilateral pleural surfaces with at least one of the following: visceral pleural tumor, invasion of the diaphragmatic muscle, or invasion of the lung; or the tumor involves any of the ipsilateral pleural surfaces, with at least one of the following: invasion of the endothoracic fascia (the membrane that surrounds the thorax), invasion into mediastinal fat with spread to the lymph nodes, but not to distant parts of the body. The cancer has also spread to the lymph nodes, but not throughout the body (T1 or T2, N1, M0; T1 or T2, N2, M0; T3, any N, M0).

Stage IV: The cancer involves any of the ipsilateral pleural surfaces, with at least one of the following: diffuse or multifocal invasion of soft tissues of the chest wall, any involvement of rib, invasion through the diaphragm to the peritoneum, invasion of any mediastinal organ(s), direct extension to the contralateral pleura, invasion into the spine, extension to the internal surface of the pericardium, pericardial effusion with positive cytology, invasion of the myocardium, and/or invasion of the brachial plexus. Stage IV can also mean that the tumor is of any size and the cancer has spread to distant lymph nodes, or the cancer has spread to other parts of the body (T4, Any N, M0; any T, N3, M0; or any T, any N, M1).

Recurrent: This is cancer that has come back after treatment. It may return in the chest or in another part of the body.

Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Sixth Edition (2002) published by Springer-Verlag New York, www.springer-ny.com.