Diagnosis and staging of anal cancer

How is it diagnosed? 

Your GP will ask you questions about your symptoms, your own medical history and your family history.

Your GP may examine you during the appointment. They may do a digital rectal examination (DRE). This involves putting a gloved finger inside the back passage (anus) to feel for any lumps. This can be uncomfortable, but it shouldn’t be painful and it’s over quickly. They may also request a blood test.

If your GP thinks that you may have cancer, they will refer you to the hospital for further tests.

Depending on your symptoms, your referral to hospital may be called an urgent referral. This means that you should get a hospital appointment or have more tests within two weeks. If you don't get a specialist appointment within two weeks, ask your GP to check for you.

If your referral is non-urgent, sometimes referred to as a routine referral, ask your GP how long you should expect to wait for an appointment.

At the hospital, you will have an anal examination, known as an anoscopy. This is done using a thin tube with a light and a camera on the end called an anoscope. They may also look at the rectum, using a longer tube. This is called a proctoscopy.

This examination will be performed by a healthcare professional known as an endoscopist. This test is usually done using a local anaesthetic, but it may be possible for you to be sedated during the test.

If the endoscopist sees anything that needs to be looked at more closely, samples (biopsies) can be taken for further tests in the laboratory.

For women, trans men and other people assigned female at birth, you may have an internal examination of the vagina as well. This is because the vagina is close to the anus.

Depending on your symptoms and test results, you may go on to have further tests. This may include a CT scan, a MRI scan or a PET-CT scan.

Staging and grading

Staging a cancer involves describing its size, where it is and whether it has spread. Knowing the stage of your cancer will help you and your healthcare team to decide on the best treatment.

There are different ways of staging anal cancer. The most common is TNM. This is explained below:  

TNM system 

• T (tumour) – describes the size and location of the tumour 

• N (nodes) - describes whether the cancer has spread to nearby lymph nodes 

• M (metastases) – describes whether the cancer has spread (metastasised) to other parts of the body
  

Number staging 

Information from the TNM staging report can be used to give a number stage: 

Stage 0 –there are abnormal cells in the lining of the anus. It is also known as anal carcinoma in situ (AIN) 

Stage 1 - the cancer only affects the anus and is smaller than 2cm in size 

Stage 2 - the cancer is bigger than 2cm in size, but has not spread into the lymph nodes or other parts of the body 

Stage 3 - the cancer has spread to nearby organs, such as the vagina, urethra or bladder, or to nearby lymph nodes 

Stage 4 - the cancer has spread to other parts of the body, for example the liver

More information

The Anal Cancer Foundation provides support and information for people living with or affected by anal cancer. 

Macmillan Cancer Support has an anal cancer forum where you can speak to people who have been affected by anal cancer.

Cancer Research UK has detailed information on scans and tests for cancer. 

Updated November 2025 

Next review November 2028