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TNM Staging

Your tests and scans give doctors information about the size of the cancer and whether it has spread to another part of your body. This is the stage of your cancer. Knowing this helps your doctors decide what treatment you need.

Doctors can use the TNM system to stage your cancer. TNM stands for Tumour, Node, Metastasis. 

Doctors might also use the number staging system. 

Tumour (T)

Tumour describes the size of the cancer. There are 5 T stages for anal cancer.


Tis is also called carcinoma in situ, anal intraepithelial neoplasia (AIN) or high grade squamous intraepithelial lesion. Some of the cells within the lining of the anus have abnormal changes.


T1 means the cancer is 2cm or less.


T2 means the cancer is larger than 2cm but smaller than 5cm.


T3 means the cancer is larger than 5cm.


T4 means the cancer is any size but it is growing into the surrounding organs, such as the bladder, urethra (the tube that carries urine from the bladder out of your body) or the vagina. 

Node (N)

Node (N) describes whether the cancer has spread to the nearby lymph nodes, such as lymph nodes near the rectum, in the pelvis or groin.

There are 2 main N stages for anal cancer.

  • N0 means there are no cancer cells in the nearby lymph nodes 
  • N1 means there are cancer cells in the nearby lymph nodes 

N1 can be further divided into a, b or c, depending on which lymph nodes the cancer cells have spread to.

Diagram showing stage 3 anal cancer

Metastasis (M)

Metastasis (M) describes whether the cancer has spread to a different part of the body.

There are 2 M stages for anal cancer:

  • M0 means the cancer hasn't spread to another part of the body
  • M1 means the cancer has spread to another part of the body, such as the liver or lungs
Diagram showing stage 4 anal cancer
Call Cancer Research UK’s information nurses on freephone 0808 800 4040 from 9am to 5pm, Monday to Friday, for more information about staging for anal cancer.


The stage of your cancer helps your doctor to decide which treatment you need. Treatment also depends on:

  • your type of cancer (the type of cells the cancer started in)
  • where the cancer is 
  • other health conditions that you have

The stage of the cancer and these other factors can also give an idea of your outlook (prognosis).

Squamous cell cancer is the most common type of anal cancer. Treatment might include:

  • chemoradiotherapy – a combination of chemotherapy and radiotherapy
  • surgery
  • chemotherapy 
  • radiotherapy

You may also have treatment as part of a clinical trial.

Last reviewed: 
26 Apr 2019
  • AJCC Cancer Staging Manual (8th Edition)
    M Amin and S Edge.
    Springer, 2017.

  • Anal cancer: ESMO-ESSO-ESTRO Clinical Practice Guidelines for diagnosis, treatment and follow-up
    R. Glynne-Jones and others
    Annals of Oncology 2014. Volume 25, Pages iii10-iii20