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Anal cancer

Published by Bupa's health information team, February 2008.

This factsheet is for people who have anal cancer, or who would like information about it.

Anal cancer is a lump created by an abnormal and uncontrolled growth of cells in the anus.

How cancer develops

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About anal cancer

Anal cancer is a rare form of cancer. Less than 800 people are diagnosed with it each year in the UK, although this number has been rising. Anal cancer is more common in women, men who have receptive anal intercourse and in people who have weakened immune systems. Anal cancer is closely linked with some strains of the human papilloma virus (HPV).

The anus is the name for the area at the very end of your bowel. The anal canal is the tube that connects the lower part of the large bowel (the rectum) to the outside of the body. It's surrounded by a muscle called the sphincter which relaxes and contracts to control your bowel movements.

The anal canal is lined with small, flat cells called squamous cells. Most anal cancers develop from these cells and are known as squamous cell carcinomas.

Where the anal canal meets the rectum is known as the transitional zone. Here, there are squamous cells and glandular cells, which produce mucus to help your faeces pass smoothly through your anus. A type of cancer called adenocarcinoma of the anus can develop from glandular cells, but this is very rare. Two types of skin cancer called basal cell carcinomas or malignant melanomas can also occur around the anus, but these are also extremely rare (for more information, see Related topics).

Symptoms

Anal cancers can cause you to have:

  • bleeding from your rectum, which you may see either in your faeces or on the toilet paper - this is the most common symptom of anal cancer
  • pain in your anal area
  • small lumps around your anus, which may be confused with piles (for more information, see Related topics)
  • discharge of mucus or a jelly-like substance from your anus
  • difficulty controlling your bowel movements (known as faecal incontinence)
  • itchiness around your anal area

Although not necessarily the result of anal cancer, if you have any of these symptoms you should visit your GP.

Causes

The precise cause of anal cancer isn't fully understood at present. The following factors may increase your chance of getting the disease.

  • Some types of human papilloma virus (HPV) - the virus that causes genital warts which is passed from person to person through sexual contact. Over eight in every 10 people who are diagnosed with anal cancer have a HPV infection in the anal area.
  • Number of sexual partners - the greater the number of sexual partners you have, the more likely you are to have had HPV infection.
  • Anal intercourse - women who have anal intercourse and men who have receptive anal intercourse are at an increased risk of developing anal cancer.
  • Cancer of the vagina, cervix or penis - if you have a history of cervical or vaginal cancer or a history of penile cancer, you may be at an increased risk of developing bowel cancer. This is because HPV is also associated with these cancers.
  • Smoking - this increases your risk of getting anal cancer.
  • Age - your risk of developing anal cancer increases with age.
  • A weakened immune system - for example, if you are taking medicines to suppress your immune system (eg after an organ transplant) or if you have HIV infection, you are at an increased risk of getting anal cancer.

Diagnosis

Your GP will ask about your symptoms and examine you. He or she will also ask you about your medical history. Your GP may refer you to a colorectal surgeon - a doctor specialising in treating conditions of the bowel. You may need to have one or more of the following tests.

  • An examination of your anus (known as a rectal examination) - your doctor will examine your anus with a lubricated gloved finger. Although a little uncomfortable this is not a painful examination.
  • To examine the area more carefully, your doctor may use a proctoscope or sigmoidoscope. These are narrow tubes with a light which allows the doctor to examine the lining of the anus and rectum and if necessary take a biopsy.
  • A biopsy - your doctor will take a small sample of tissue from your anal area. This will be sent to a laboratory for testing.

If these tests show that you have anal cancer then further tests will be arranged to see how big the cancer is and whether it has spread. These might include:

  • A CT (computerised tomography) scan - this uses X-rays to build up a three-dimensional picture of the body (for more information, see Related topics).
  • An MRI (magnetic resonance imaging) scan - this uses magnets and radiowaves to produce two- and three-dimensional pictures of the inside of your body (for more information, see Related topics).
  • An ultrasound scan - this uses sound waves to produce an image of your abdomen, or you may have a rectal ultrasound where a small probe will be passed into your anus for the scan (for more information, see Related topics).

Treatment

There are different types of treatment available for rectal cancer depending on how big the tumour is and whether it has spread. Occasionally, if the cancer is very small, it can be removed by a small operation, however in many cases other treatments involving chemotherapy and radiotherapy are required. Your team of doctors will recommend the best treatment option for you.

Non-surgical treatments

The most common form of treatment for anal cancer is a combination of both chemotherapy and radiotherapy to kill the cancer cells. This is known as chemoradiation. They may be given to you at the same time or following one another.

Chemotherapy uses anti-cancer drugs (known as cytotoxic drugs) which can be given as an injection into one of your veins or as tablets.

Radiotherapy uses high-energy rays to kill the cancer cells. This is usually given by external beam radiotherapy which is a little like having an X-ray and is quick and painless, although it does have some side-effects. Occasionally internal radiotherapy (brachytherapy) may be used, which involves radioactive wires being placed temporarily in the area of the cancer.

Both treatments have side-effects, but having both treatments together can sometimes make these side effects more severe. They may include:

  • changes in your bowel habits, such as diarrhoea
  • blistering and soreness of the skin around your anus
  • increased risk of infections whilst on treatment
  • tiredness
  • loss of appetite
  • feeling sick
  • sore mouth and small mouth ulcers
  • thinning or loss of hair
  • in women, narrowing and dryness of your vagina

Surgery

Chemoradiation is usually the preferred method of treating anal cancer. However, surgery may sometimes be needed to remove the cancer. There are two types of surgery. The operation you have depends on the size and position of your cancer.

An operation called a local resection is used to remove a small tumour and some of the surrounding tissue. This can only be done when your anal sphincter won't be affected by the surgery. This type of surgery usually doesn't affect your ability to pass a bowel movement.

Alternatively, the anus, rectum and part of the bowel can be removed by surgery. This is called an abdominoperineal resection. Without your rectum and anus you can't pass a bowel movement and so the end of your bowel will be brought out onto the skin on the surface of your abdomen. This is called a colostomy; the opening of the bowel is known as a stoma. A bag is worn over the stoma and this collects your faeces outside your body. People with colostomies are able to live normal lives, including having sex and participating in sports.

After your treatment

After your treatment has been completed you will still see a doctor for regular check-ups. These may include answering some questions about symptoms as well as an examination by the doctor and sometimes scans. The follow-up appointments will get less frequent as time passes after your treatment.

Prevention

One way to reduce your risk of getting anal cancer is to avoid getting HPV, which is passed on through sexual contact. It's important to remember that you can have the HPV virus but not have genital warts or any other symptoms. To reduce your risk of HPV infection:

  • use condoms when having sex
  • limit the number of sexual partners you have
  • refrain from having anal intercourse

Stopping smoking, if you smoke, will reduce your risk of getting anal cancer.

Further information

Related topics

Sources

  • Urions H, Bendell J. Anal Cancer: An Overview. The Oncologist 12:524-534. 2007
  • Johnson L et al. Anal cancer incidence and survival: the surveillance, epidemiology, and end results experience, 1973-2000. Cancer. 101; 2:281-288. 2004
  • Cassidy J, Bissett D, Spence R. Oxford Handbook of Oncology. 1st ed. Oxford: Oxford University Press, 2002
  • Bowel Cancer UK. www.bowelcanceruk.org.uk, accessed 10 July 2007
  • Cancerbackup. www.cancerbackup.org.uk, accessed 20 Aug 2007
  • The American Cancer Society. www.cancer.org, accessed 22 Aug 2007
  • Cancer Research UK. www.cancerhelp.org.uk, accessed 20 Aug 2007

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. It has also been reviewed by Cancerbackup. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: February 2008.

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