Bowel cancer staging

In order to determine the best treatment for your bowel cancer, you will undergo various tests to find out the size and position of the cancer, and whether it has spread.

This process is called ‘staging’. You will probably also have blood tests to check your general health, and a CT (computerised tomography) scan, MRI (magnetic resonance imaging) scan or ultrasound scan that enables the doctors to look at the cancer in more detail.


The stage of your bowel cancer can be described as stage I – IV (or 1 – 4). This international system is increasingly being used when talking to patients, however the original Dukes’ staging system is also still used (Dukes A, B, C or D).


You will sometimes see the TNM staging report written with a lower case letter in front of it. A cTNM means that it is based on the clinical findings of your scans and biopsies before you start your treatment. A pTNM classification is based on the full findings of both the pre-treatment investigations, and confirmed by a pathological assessment (of tissue under the microscope) following your surgery.


Stage 0 or ‘carcinoma in situ’ means that the cancer cells are contained in the inner lining of the bowel and there is very little risk of any cancer cells having spread.


DukeStagingC-DDuke staging diagram

TNM – is a shorthand description of the staging classification, which helps the 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.