Size of the bowel cancer tumour, its position and whether it has spread

If you are diagnosed with bowel cancer, you will firstly need to have tests to determine the size of the cancer tumour, its position and whether it has spread.  This process is known as 'staging'.
 
Your doctor needs to know the extent (stage) of the disease to plan the best treatment.  The stage is based on whether the tumour has invaded nearby tissues, whether the cancer has spread and, if so, to what parts of the body.
 
Your doctor may order some of the following tests:

  • Blood tests: Your doctor checks for carcinoembryonic antigen (CEA) and other substances in the blood.  Some people who have bowel cancer or other conditions have a high CEA level.  You may also have blood test that measures chemicals that are normally found in your liver, known as a Liver Function Test.  An abnormal result can be a sign the cancer has spread to the liver.
  • Colonoscopy: If colonoscopy was not performed for diagnosis, your doctor checks for abnormal areas along the entire length of the colon and rectum with a colonoscope.
  • Endorectal ultrasound: An ultrasound probe is inserted into your rectum.  The probe sends out sound waves that people cannot hear.  The waves bounce off your rectum and nearby tissues, and a computer uses the echoes to create a picture.  The picture may show how deep a rectal tumour has grown or whether the cancer has spread to lymph nodes or other nearby tissues.
  • Chest x-ray: X-rays of your chest may show whether cancer has spread to your lungs.
  • CT scan: An x-ray machine linked to a computer takes a series of detailed pictures of areas inside your body.  You may receive an injection of dye.  A CT scan may show whether cancer has spread to the liver, lungs, or other organs.
Your doctor may also use other tests (such as an MRI) to see whether the cancer has spread.
 
Sometimes staging is not complete until after surgery to remove the tumour.
 
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The following stages are used for bowel cancer
 

Stage 0 (Carcinoma in Situ)
In stage 0, abnormal cells are found in the mucosa (innermost layer) of the bowel wall.  These abnormal cells may become cancer and spread.  Stage 0 is also called carcinoma in situ.

About Bowel Cancer Stage 0 770new

Stage I
In stage I, cancer has formed in the mucosa (innermost layer) of the colon wall and has spread to the submucosa (layer of tissue under the mucosa).  Cancer may have spread to the muscle layer of the colon wall.

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Stage II
Stage II bowel cancer is divided into stage IIA, stage IIB, and stage IIC.

  • Stage IIA: Cancer has spread through the muscle layer of the bowel wall to the serosa (outermost layer) of the bowel wall.
  • Stage IIB: Cancer has spread through the serosa (outermost layer) of the bowel wall but has not spread to nearby organs.
  • Stage IIC: Cancer has spread through the serosa (outermost layer) of the bowel wall to nearby organs.
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Stage III
Stage III bowel cancer is divided into stage IIIA, stage IIIB, and stage IIIC.

In stage IIIA:

  • Cancer may have spread through the mucosa (innermost layer) of the colon wall to the submucosa (layer of tissue under the mucosa) and may have spread to the muscle layer of the colon wall. Cancer has spread to at least one but not more than 3 nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes; or
  • Cancer has spread through the mucosa (innermost layer) of the colon wall to the submucosa (layer of tissue under the mucosa). Cancer has spread to at least 4 but not more than 6 nearby lymph nodes.
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In stage IIIB:
  • Cancer has spread through the muscle layer of the colon wall to the serosa (outermost layer) of the colon wall or has spread through the serosa but not to nearby organs. Cancer has spread to at least one but not more than 3 nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes; or
  • Cancer has spread to the muscle layer of the colon wall or to the serosa (outermost layer) of the colon wall. Cancer has spread to at least 4 but not more than 6 nearby lymph nodes; or
  • Cancer has spread through the mucosa (innermost layer) of the colon wall to the submucosa (layer of tissue under the mucosa) and may have spread to the muscle layer of the colon wall. Cancer has spread to 7 or more nearby lymph nodes.
About Bowel Cancer Stage IIIB 770new
In stage IIIC:
  • Cancer has spread through the serosa (outermost layer) of the colon wall but has not spread to nearby organs. Cancer has spread to at least 4 but not more than 6 nearby lymph nodes; or
  • Cancer has spread through the muscle layer of the colon wall to the serosa (outermost layer) of the colon wall or has spread through the serosa but has not spread to nearby organs. Cancer has spread to 7 or more nearby lymph nodes; or
  • Cancer has spread through the serosa (outermost layer) of the colon wall and has spread to nearby organs. Cancer has spread to one or more nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes.
About Bowel Cancer Stage IIIC 770new

Stage IV (also known as metastatic, advanced or secondary bowel cancer)
Stage IV colon cancer is divided into stage IVA and stage IVB.

  • Stage IVA: Cancer may have spread through the colon wall and may have spread to nearby organs or lymph nodes. Cancer has spread to one organ that is not near the colon, such as the liver, lung, or ovary, or to a distant lymph node.
  • Stage IVB: Cancer may have spread through the colon wall and may have spread to nearby organs or lymph nodes. Cancer has spread to more than one organ that is not near the colon or into the lining of the abdominal wall.
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Recurrence
Recurrent bowel cancer is cancer that has recurred (come back) after it has been treated.  The cancer may come back in the bowel or in other parts of the body, such as the liver, lungs, or both. 

The TNM Bowel Cancer Staging System 
 
Another staging system being used more often is called the TNM system.
 
TNM is a shorthand description of the staging classification, which helps specialists to understand very quickly what your cancer looks like.
 
T describes tumour size and how far it has grown into - and through - the bowel wall, using a scale of T0 to T4
N describes lymph node involvement - from N0 which means that no lymph nodes are affected, to N2 where there are 4 or more lymph nodes affected. 
M describes whether distant metastases (secondary tumours in other parts of the body) are present or not.  M0 means that there is no evidence of the cancer having spread, while M1 means that there is. 
 
Within any category of the TNM scoring system, the use of an X score means that it has not been possible to assess the presence of cancer within the area described.
 
You may also hear about the Dukes' system or the Australian Clinico-Pathological Staging (ACPS) system.  
 
Ask your doctor to explain the stage of your cancer in a way you can understand.  This will help you to choose the best treatment for your situation.
 
The following diagram may be of assistance in comparing the various systems used to to stage bowel cancer.  
 
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