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Cancer staging and grading

Cancer is caused by the cells of the body changing so that they grow in an uncontrolled way. This factsheet is to help you understand how doctors and surgeons stage and grade cancer.

About cancer

A cancerous (malignant) tumour is a lump created by an abnormal and uncontrolled growth of cells.

Cancerous tumours can grow through organs and spread to other parts of your body (through the bloodstream or the lymph system) where they may grow and form secondary tumours. This spread of cancer is called a metastasis.

Diagnosis

If your doctor or surgeon suspects that you have cancer you will need to have tests to confirm a diagnosis. The tests will be specific for the type of cancer you may have. At this point your doctor or surgeon will also find out the stage and/or grade of your cancer.

Staging and grading records the size of a tumour, how far it has grown and how quickly it is growing. This helps your doctor or surgeon communicate about your treatment and provide standardised, tailored care.

Your doctor or surgeon will need to know the stage and/or grade of your cancer to plan your treatment. If the cancer has spread, your treatment will need to target all the areas affected. You may need systemic treatments (such as chemotherapy) which treat the whole body.

For information on the tests for specific cancers, please see Related topics.

Staging

Staging measures how far a cancer has progressed. There are two main ways of staging your cancer.

TNM staging system

Doctors and surgeons use TNM cancer staging to describe solid tumours which affect the breast, head, neck and lungs (except small-cell) and genito-urinary cancers such as bladder, testicular and ovarian cancers. Staging of bowel cancers, lymphomas or leukaemias may be described in a different way.


The primary tumour (T)

The primary tumour is where the cancer started. A tumour can grow into nearby tissues and organs. This part of the staging system generally describes the size or growth of the tumour. Sometimes the site of the tumour, for example when diagnosing lung cancer, may mean a cancer is more serious, and the T scale is used to describe the site and not the size of the tumour.

T in TNM staging

The T stage will be numbered between 1 and 4. For example, T1 is a small or early stage cancer, T4 is a large or advanced stage cancer. Sometimes a and b are also used to define the cancer further, such as T2a and T2b. This will be specific for the cancer you have. If Tx is used, this means the stage of the cancer isn't clear after the tests you have had. Ask your doctor for more information.

Your cancer may be termed TIS or CIS. This stands for tumour or carcinoma in situ. This means the cancer is in one small area and has not yet spread. This may also be called stage 0.

Lymph nodes (N)

The lymph nodes are small bean-shaped organs. They are part of the lymphatic system, which is made up of lymph nodes connected by lymph vessels. The lymph nodes and vessels contain fluid called lymph which consists of cells which fight infection.

N in TNM staging

This part of the TNM staging system describes whether the cancer has spread to the lymph nodes. The node or N will be numbered between 0 and 3 to record how many lymph nodes have cancer. For example, N0 means there is no cancer in the lymph nodes and N3 will mean there are many lymph nodes affected by the cancer.

Surgery may be needed to remove lymph nodes which have cancer, but this can be difficult. Some lymph nodes are attached to a part of the body from which they can't be removed or there is no access. If this is the case, even though there may only be a few lymph nodes affected by cancer, it may be referred to as N3. A number of lymph nodes which can be removed may be of a lower stage, such as N1. If Nx is used, it means the tests you have had aren't clear and it's uncertain if the lymph nodes are affected or not.

If your cancer has spread to the lymph nodes it may mean the cancer has spread to other areas of the body too. It may not be possible to know for certain if the cancer has spread to other areas if tests don't detect it. For this reason you may need "adjuvant" (preventative) treatment to kill any cancer that may have broken away from the primary tumour.

Presence of metastatases (M)

If the cancer has spread (metastasized) this will affect your treatment. This may be to one or more areas far from where the cancer started (the primary tumour).

M in TNM staging

M may be 0 or 1. If the cancer has spread it is called M1, if it has not spread it is called M0. If Mx is used this means it's not clear if the cancer has spread.

Number staging system

Some cancers, such as lymphoma, thymus and liver cancer, may be numbered 1 to 4 and won't use the TNM system. Stage 1 refers to a small tumour, which hasn't spread to the lymph nodes, this may also be called early stage. Stage 4 refers to a cancer which has spread to other major organs in the body and is called advanced stage. Stages 1 to 4 may be used with letters, for example stage 2a or 2b, for certain cancers to define the cancer further if it's affected in a certain area but not another part. This will be specific for the cancer you have.

There are other staging systems which may be used for different types of cancer.

Dukes staging system

The staging of bowel cancer currently uses the Dukes lettered (A-D) system.

Dukes A - the cancer is within the bowel

Dukes B - the cancer has spread into the muscle but is not found in the lymph nodes

Dukes C - one or more lymph nodes near the bowel are affected in addition to the bowel

Dukes D - the cancer has spread to another part of the body such as the liver or lungs (secondary cancer)

This system is gradually being replaced by the TNM staging system.

If you are unsure what the stage is of the cancer you have, ask the doctor or surgeon who is treating you for advice.

Grading

Cancers may also be graded. A sample of cancer cells may be taken to diagnose cancer - this is called a biopsy. The cells are sent to a laboratory for testing. These cells will look different under the microscope as your cancer develops. The results will help your doctor or surgeon understand how quickly your cancer is likely to develop and spread.

The main grading system in use is as follows.

Low grade, or grade 1, refers to cancers which are slow growing and the cells look much like normal, healthy cells. They are less likely to spread. They may also be called "well differentiated".

Moderate (intermediate) grade, or grade 2, are cancer cells which look much less normal and are growing slightly quicker. They may also be called "moderately differentiated".

High grade, or grade 3 cancer cells don't look like normal cells and are more likely to grow quickly and spread. They may also be called "poorly differentiated" or sometimes "undifferentiated".

If you are unsure what the grading is of the cancer you have, ask the doctor or surgeon who is treating you for advice.

Further information

Cancerbackup

0808 800 1234

Sources

  • Cancer. Cancerbackup. www.cancerbackup.org.uk, accessed 6 December 2007
  • Cancer. Cancer Research UK. www.cancerhelp.org.uk, accessed 5 December 2007
  • Cassidy J, Bissett D and Spence RAJ Obe, Oxford Handbook of Oncology: Oxford: Oxford University Press, 2002:78-79
  • Souhami R, Tobias J. Cancer and its management. 5th ed. Oxford, 2005:42-56

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