Staging and grading of anal cancer
The stage and grade of anal cancer describes its size, whether it has spread and how quickly it may develop. The results of the tests and scans you have had help your doctor decide on the stage of the cancer.
Stages of anal cancer
The results of the tests and scans you have had help your doctor decide on the stage of the cancer.
The stage of a cancer describes its size and if it has spread from where it started. Knowing the stage helps the doctors decide on the best treatment for you.
The staging systems most commonly used for anal cancer are:
- TNM staging
- number staging.
Bowel cancer is a general term for a cancer that starts in either the colon or the rectum.
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 anal cancer forum to talk to people who have been affected by anal cancer, share your experience, and ask an expert your questions.
TNM staging system
T – describes the size of the tumour 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.
T – Tumour
Tis – The cancer is at its earliest stage. There are cancerous changes to some of the cells, but they are only in the lining of the anus. This is sometimes called in situ.
- T1 – The tumour is 2cm or smaller.
- T2 – The tumour is bigger than 2cm but not over 5cm.
- T3 – The tumour is bigger than 5cm.
- T4 – The tumour can be any size, and has started to grow into nearby structures, such as the vagina, bladder or the tube that carries urine from the bladder (urethra).
N – Nodes
This describes whether any lymph nodes near the anus contain cancer cells.
- NX – The lymph nodes were not examined.
- N0 – There is no cancer in the lymph nodes.
- N1 – There is cancer in the lymph nodes close to or further from the anus.
Stage N1 can be broken down into stages called N1a, b or c depending on which lymph nodes in the groin and pelvis have cancer cells in them.
M – Metastasis
Metastasis means that the cancer has spread to other parts of the body.
- M0 – The cancer has not spread to other parts of the body.
- M1 – The cancer has spread to other parts of the body, such as the liver or the lymph nodes in the tummy (abdomen).
Number staging system
Stage 1 anal cancer
The cancer only affects the anus. It is 2cm or smaller.Stage 2 anal cancer
- Stage 2 is divided into:
- Stage 2a – The cancer is bigger than 2cm but not over 5cm and has not spread.
- Stage 2b – The cancer is bigger than 5cm and has not spread to any lymph nodes.
Stage 1 and 2 is sometimes called early anal cancer.
Stage 3 anal cancer
Stage 3 is divided into:
- Stage 3a – The cancer is 5cm or smaller and has spread to the lymph nodes near the rectum and in the groin or pelvis.
- Stage 3b – The cancer is any size and has spread to nearby organs such as the bladder, urethra or vagina but has not spread to any lymph nodes.
- Stage 3c – The cancer is bigger than 5cm. Or it can be any size but has grown into areas nearby such as the vagina, bladder or urethra. The cancer has spread to lymph nodes in the groin and pelvis.
Stage 3 is sometimes called locally advanced cancer.
Stage 4 anal cancer
The cancer has spread to other parts of the body, such as the liver or lungs. It is sometimes called advanced or metastatic cancer.Grading of anal 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)
The cancer cells look similar to normal cells (called well differentiated). They grow slowly and are less likely to spread.
Grade 2 (moderate-grade)
The cancer cells look more abnormal. They are likely to grow faster than a low grade cancer.
Grade 3 (high-grade)
The cancer cells look very abnormal (called poorly differentiated). They grow more quickly and are more likely to spread.
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 anal cancer information. If you would like more information about the sources we use, please contact us at informationproductionteam@macmillan.org.uk
S Rao, MG Guren, K Khan et al. Anal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. 2021. European Society of Medical Oncology. Available from: www.esmo.org/guidelines/guidelines-by-topic/esmo-clinical-practice-guidelines-gastrointestinal-cancers/anal-cancer [accessed January 2023].
O Dahl, MP Myklebust, JE Dale et al. Evaluation of the stage classification of anal cancer by the TNM 8th version versus the TNM 7th version. 2020. Acta Oncologica, 59(9), 1016–1023. Available from: www.tandfonline.com/doi/full/10.1080/0284186X.2020.1778180 [accessed December 2022].
Date reviewed
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