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Anal cancer

Expert reviewer, Dr Sunil Skaria, Consultant in Clinical Oncology
Next review due June 2024

Anal cancer is a type of cancer that starts in your bottom. It develops in your anus, the opening to the exterior at the end of your bowel. It happens when cells in your anus start growing abnormally and out of control, which causes symptoms, such as pain and bleeding from your bottom.

About anal cancer

Anal cancer is rare – about 1,000 people are diagnosed with it each year in the UK. But more people have got anal cancer in recent years, particularly women.

Types of anal cancer

There are different types of anal cancer, which include the following.

  • Squamous cell carcinoma. This is the most common type. It develops in the cells that line your anal canal and the cells of your anal margin. Your anal canal is the tube that connects the lower part of your large bowel (rectum) to the outside of your body. The anal margin is the darker-coloured skin that surrounds the opening to your anus.
  • Adenocarcinoma. This develops in cells that produce mucus within your anal canal. Doctors treat it in the same way as rectal cancer.
  • Basal cell carcinoma. This is a type of skin cancer that can develop in the skin around your anus.
  • Malignant melanoma. This is another type of skin cancer that you can get around your anus. It starts in cells called melanocytes. Doctors treat it in the same way as other melanomas.

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Causes of anal cancer

The main cause of anal cancer is thought to be the human papilloma virus (HPV). This is a sexually transmitted virus, which is also linked to cervical cancer and genital warts. You’re more at risk of an HPV infection and anal cancer if you:

  • have sex with a lot of people
  • have anal sex – particularly if you’re a man who has sex with other men
  • have had vaginal cancer or cervical cancer

There are some other things that can increase your risk of anal cancer. For example, if you have HIV/AIDS or if your immune system is suppressed for some other reason.

Women are more likely than men to develop anal cancer. You’re also more likely to get it if you smoke, and your risk increases as you get older.

Symptoms of anal cancer

The most common symptoms of anal cancer are:

  • bleeding from your bottom – you may see blood in your poo or on toilet paper
  • pain around your bottom

Other symptoms of anal cancer include:

  • feeling itchy around your bottom
  • a discharge coming from your anus
  • a small lump or lumps or ulcers around your anus
  • difficulty controlling when you poo, which is called faecal incontinence

If you have these symptoms and they don’t seem to be getting better, go and see your GP. Bleeding from your bottom is a very common symptom linked to lots of other conditions. Most of the time, it’s caused by something less serious such as piles (haemorrhoids). But it’s worth getting checked by a doctor. Don’t put it off – cancers are usually easier to treat if you catch them early.

Diagnosis of anal cancer

Your GP will ask about your symptoms and examine you. They’ll ask about your medical history too.

Your GP may ask to examine your bottom to check if they can feel anything wrong. They’ll do this by feeling inside your bottom with their finger (they’ll wear a glove and use lubrication). Although it might feel a little uncomfortable, it shouldn’t be painful.

Your GP may also examine inside your vagina to check if a tumour has spread to here.

Tests to diagnose anal cancer

Your GP may refer you to hospital for further tests. Or they may refer you to see a doctor who specialises in conditions that affect the bowel.

You may have a blood test to check your general health and to rule out other health conditions that could cause your symptoms.

To test for anal cancer, a doctor will put a tube into your bottom to look inside your bowel. They may use one of the following procedures.

  • A proctoscopy – your doctor will use a small tube to look inside your bottom.
  • A sigmoidoscopy – your doctor will use a longer tube to look further inside your large bowel.
  • A colonoscopy – your doctor will look at the whole of your large bowel.

You’ll usually have these tests as an out-patient (you won’t need to stay in hospital). They can be uncomfortable but shouldn’t be painful. Your doctor may take a small sample of tissue (a biopsy) during the test. They’ll send this to a laboratory for testing to find out whether the cells are cancerous or not.

You may also have a test under general anaesthesia to allow your doctor to do a more thorough examination and to take a biopsy.

Staging

If tests show that you have anal cancer, you’ll need to have more tests to find out how big it is and if it’s spread. This process is known as staging. You may have the following tests in different parts of your body:

  • a computer tomography scan (CT scan)
  • a chest X-ray
  • an MRI scan
  • a PET-CT scan (a type of CT scan that uses a radioactive dye to show up cancer cells)
  • an ultrasound of your bottom
  • tests on your lymph nodes – a doctor will use a small needle to take a sample of cells

Treatment of anal cancer

A multidisciplinary team (MDT) will manage your treatment. An MDT is a team of healthcare professionals with different specialities, including doctors specialised in diagnosing and treating anal cancers, and specialist nurses. Your treatment will depend on the type of anal cancer you have, and how far it’s spread. Your doctor will discuss what your options are. After you've finished your treatment, you’ll need to have regular check-ups with your doctor.

Chemoradiotherapy

The most common treatment for anal cancer is a combination of chemotherapy and radiotherapy, which is called chemoradiotherapy. This uses medicines and radiation together to destroy cancer cells. You’ll have a treatment plan that’s tailored to your needs, depending on services and guidelines available in your local area.

You’ll usually have your treatment over five weeks, with chemotherapy on the first and last weeks, and radiotherapy throughout. And you’ll usually have two different chemotherapy medicines. You may have these as an injection or as a drip into a vein in your arm. You’ll usually have the radiotherapy every weekday for the five-week treatment period.

You’ll usually have chemotherapy in a day unit at the hospital, and radiotherapy as an out-patient. This means you won’t usually need to stay overnight in hospital. But you will need to be able to travel to the hospital every weekday during your treatment period.

Surgery

Sometimes, your doctor may recommend you have surgery to remove your cancer. The operation you have will depend on the stage of your cancer.

Local excision

Your MDT might offer you surgery if your tumour is small and just affects the area around the opening to your bottom (the anal margin). This is called a local excision. A surgeon will remove the tumour along with some normal skin and tissue around it. As it doesn’t involve any of the muscles in your bottom, you should still be able to poo normally after the operation.

Abdominoperineal resection (AP resection)

Your MDT may advise surgery to remove the cancer if you’ve had chemoradiotherapy that hasn’t worked or if your cancer has come back after treatment. It isn’t very common. In this surgery, which is called abdominoperineal resection, a surgeon will remove your anus, rectum and part of your bowel. It’s often called ‘salvage surgery’ because it’s a second chance of curing your cancer when other treatment has failed.

As part of this operation, you’ll need to have a colostomy. This is when the new end of your bowel is brought out through an opening in your skin and attached to the surface of your tummy (abdomen). The opening is known as a stoma. You’ll need to wear a bag over your stoma, which will collect poo. It may take a while to adjust to living with a stoma, but your doctor or stoma nurse will give you help and advice.

Prevention of anal cancer

Vaccination against HPV can help to protect against anal cancer. In the UK, this is offered to all children aged 12–13. You can also get the HPV vaccine free through a sexual health clinic if you’re a man who has sex with men, and you’re under 45. Anyone can pay to have the vaccine privately through a pharmacy, health clinic, or sometimes your GP.

Other things you can do to reduce your risk of anal cancer include:

  • wearing condoms when you have sex
  • giving up smoking if you smoke.

Living with anal cancer

You may need to make some changes to your diet while you’re having treatment for anal cancer. Both chemotherapy and radiotherapy can cause diarrhoea – and because you’re likely to have the two treatments together, the diarrhoea can be hard to cope with.

It might help to eat less fibre during your treatment and for a few weeks afterwards while you recover. This means not eating wholegrain cereals or breads, or fruit and vegetables that are high in fibre. Once your digestion has settled down again, you can gradually reintroduce more fibre to your diet.

If you need to have a colostomy, it’s likely you’ll need to make a number of changes – including to your diet. This can take a while to come to terms with. For more information about living with a stoma, see our section: Related information.

After a diagnosis of anal cancer, you're likely to have a range of emotions. As well as the emotional aspects, there can be a lot of practical issues to sort out. These include telling other people and taking time off work. Talk to your family and friends to help them to understand what you’re going through and how you’re feeling. Organisations and support groups can also be a great source of information and support. See our section: Other helpful websites.

For more articles on the various aspects of living with cancer, see our section: Related information.

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Related information


  • Discover other helpful health information websites.
    • Anal cancer. BMJ Best Practice. bestpractice.bmj.com, last reviewed 3 April 2021
    • Anal cancer. Cancer Research UK. cancerresearchuk.org, last reviewed 9 April 2019
    • Gastrointestinal tract (lower) cancers – recognition and referral. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised February 2021
    • Anal cancer. Oxford Handbook of Oncology. Oxford Medicine Online. oxfordmedicine.com, published online October 2018
    • Anal carcinoma. Patient. patient.info, last edited 28 December 2017
    • Human papillomavirus (HPV) vaccination. Patient. patient.info, last edited 12 February 2020
    • Geh I, Gollins S, Renehan A, et al. Association of Coloproctology of Great Britain & Ireland (ACPGBI): Guidelines for the management of cancer of the colon, rectum and anus (2017) – anal cancer. Colorectal Dis 2017; 19(Suppl 1):82–97. doi: 10.1111/codi.13709
    • Who can have the HPV vaccine? Jo's Cervical Cancer Trust. www.jostrust.org.uk, updated 14 July 2020

  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, June 2021
    Expert reviewer, Dr Sunil Skaria, Consultant in Clinical Oncology
    Next review due June 2024

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