Staging and grading of bowel cancer
Stages of bowel cancer
In the video below, oncologist Rebecca talks about how bowel cancer is staged. She explains the difference between early, locally advanced and advanced bowel cancer.
The stage of a cancer describes its size and whether it has spread. Knowing the stage of the cancer helps doctors decide on the best treatment for you. The most commonly used staging system is the TNM system (see below). TNM stands for tumour, nodes and metastases.
The term bowel cancer is normally used to talk about:
We have separate information about:
We understand that waiting to know the stage and grade of your cancer can be a worrying time. We are here if you need someone to talk to. You can:
- call the Macmillan Support Line for free on 0808 808 00 00
- chat to our specialists online
- visit our bowel (colon and rectal) cancer forum to talk to people who have been affected by bowel cancer, share your experience, and ask an expert your questions.
TNM staging system
T – describes how far the tumour has grown into the wall of the bowel, and whether it has grown into nearby tissues or organs.
N – describes whether the cancer has spread to the lymph nodes.
M – describes whether the cancer has spread to another part of the body such as the liver or lungs (secondary or metastatic cancer).
T – Tumour
The bowel wall is made up of layers of different tissues.
- Tis means the cancer is at its earliest stage (in situ). It is growing into the mucosa but no further.
- T1 means the tumour is only in the inner layer of the bowel (submucosa).
- T2 means the tumour has grown into the muscle layer of the bowel wall but no further.
- T3 means the tumour has grown through the muscle layer of the bowel and into the outer layer of the bowel wall (serosa).
- T4 means the tumour has grown through the outer layer of the bowel wall (serosa) and into the tissue layer covering the outside of the bowel and other organs (peritoneum). A tumour at this stage can be described as T4a or T4b:
- T4a means the tumour has caused a hole in the bowel wall (perforation) and cancer cells have spread outside the bowel.
- T4b means it has grown into other nearby structures, such as other parts of the bowel or nearby organs.
Cross-section diagram showing the different layers of the bowel and the different T stages of cancer
N – Nodes
- N0 means no lymph nodes contain cancer cells.
- N1 means there are cancer cells in up to 3 nearby lymph nodes or there are cancer cells in the tissues around the bowel.
- N2 means there are cancer cells in at least four or more nearby lymph nodes.
M – Metastases
- M0 means the cancer has not spread to distant organs.
- M1 means the cancer has spread to distant organs such as the liver or lungs or it has spread to distant parts of the tissue that covers the outside of the bowel and other organs (peritoneum).
Number staging system
Information from the TNM system can be used to give a number stage from 0 to 4.
Stage 0 bowel cancer
Stage 1 bowel cancer
Stage 2 bowel cancer
The cancer has grown through the muscle wall or through the outer layer of the bowel and may be growing into tissues nearby. The cancer has not spread to the lymph nodes or elsewhere (T3 N0 M0 or T4 N0 M0).
Stage 1 and 2 bowel cancer is sometimes called early bowel cancer.
Stage 3 bowel cancer
The tumour is any size and has spread to lymph nodes nearby but has not spread anywhere else in the body (Any T N1 M0 or Any T N2 M0).
Stage 3 cancers are sometimes called locally advanced cancer.
Stage 4 bowel cancer
The tumour is any size. It may have spread to nearby lymph nodes. The cancer may have spread to distant parts of the tissue that covers the outside of the bowel and other organs (peritoneum). Or, it has spread to other parts of the body such as the liver or lungs (Any T Any N M1).
Stage 4 cancer is sometimes called advanced or metastatic cancer.
Grading of bowel cancer
The grade describes how the cancer cells look and behave compared to normal cells. A doctor called a pathologist, who specialises in cells, looks at a sample of the cancer cells under a microscope to find the grade of your cancer.
Grade 1 (low-grade)
Grade 2 (moderate-grade)
Grade 3 (high-grade)
Checking the blood vessels and nerves
The pathologist also examines the cancer and surrounding tissues removed during surgery. They check whether the cancer cells have spread into blood vessels or nerves within the tissues. If there are cancer cells here, there is more risk of the cancer spreading to other parts of the body.
This information helps you and your doctor decide about having further treatment that aims to cure the cancer.
About our information
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer.
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References
Below is a sample of the sources used in our bowel cancer information. If you would like more information about the sources we use, please contact us at
informationproductionteam@macmillan.org.uk
National Institute for Health and Care Excellent (NICE). Colorectal cancer. NICE guideline [NG151]. Updated December 2021. Available from: www.nice.org.uk/guidance/NG151 [accessed Jan 2023].
Cervantes A, Adam R, Rosello S, et al. Metastatic colorectal cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Annals of Oncology. 2023;34(1):10-32. Available from: www.annalsofoncology.org [accessed Jan 2023].
Date reviewed
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