TNM staging for anal cancer

The stage of a cancer tells you how big it is and how far it has spread. It helps your doctor decide the best treatment for you.

TNM system stands for Tumour, Node and Metastasis. Doctors use the TNM system to stage your cancer. Doctors may also use the number system.

Tumour (T)

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

Tis 

Tis means a high-grade squamous intraepithelial lesion. This was previously called carcinoma in situ or anal intraepithelial neoplasia (AIN) 2-3. It means some of the cells within the lining of the anus have abnormal changes.

T1

T1 means the cancer is 2cm or less.

T2

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

T3

T3 means the cancer is larger than 5cm.

T4

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.

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

Treatment

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.