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The anus is the name for the muscular opening at the very end of the large bowel. It is controlled by a ring of muscle called a sphincter that opens and closes to control bowel movements. The area that connects the anus to the rectum is called the anal canal and is around 3–4 cm (1–1½in) long.
Cancer of the anus is rare. Around 1,000 people are diagnosed with anal cancer each year in the UK. The most common type of anal cancer is squamous cell carcinoma. Other rarer types are basal cell carcinoma, adenocarcinoma and melanoma. Early diagnosis and treatment is important to give the best chance of cure.
Anal cancer is slightly more common in women than in men. Many factors can increase your risk of developing anal cancer. These include:
Although these factors can increase a person’s risk of anal cancer, many people will not have these risk factors and the cause of their cancer remains unknown.
The most common symptoms of anal cancer include:
If you are concerned about any symptoms, the best first step is to see you GP who will examine you and refer you to a colorectal specialist. At the hospital, the specialist will examine you and ask about your general health and any previous medical problems. They will do some tests before they can make a firm diagnosis of anal cancer.
This is also sometimes known as a PR examination. A doctor examines your back passage with a gloved finger. Women may also have an internal examination of their vagina, as the vaginal wall is very close to the anal canal.
The doctor will put a thin tube into your back passage to examine the anal canal and rectum. This is called a proctoscopy. A small sample of tissue is taken from the tumour to be examined under a microscope (biopsy). This can be done under local or general anaesthetic. Sometimes a biopsy can be taken without needing to use a proctoscope.
If the tests show that you have anal cancer, you will need further tests to find out more about the position of the cancer and to see if it has begun to spread.
A CT scan takes a series of x-
You may be given a drink or injection of a dye that allows particular areas to be seen more clearly. For a few minutes, this may make you feel hot all over. If you are allergic to iodine or have asthma you could have a more serious reaction to the injection, so it’s important to let your doctor know beforehand.
This test is similar to a CT scan but uses magnetism, instead of x-
Before having the scan, you’ll be asked to remove any metal belongings, including jewellery. Some people are given an injection of dye into a vein in the arm. This is called a contrast medium and can help the images from the scan show up more clearly. During the test you will be asked to lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It’s painless but can be slightly uncomfortable, and some people feel a bit claustrophobic during the scan. It’s also noisy, but you’ll be given earplugs or headphones. You'll be able to hear, and speak to, the person operating the scanner.
This is a combination of a PET scan, which uses low-
This uses sound waves to form a picture. A small probe that produces sound waves is passed into the back passage (rectum). This scan can show the size and extent of the tumour.The test is painless and takes about 30 minutes.
The stage of a cancer is a term used to describe its size and whether it has spread beyond its original site. Knowing the particular type and stage of the cancer helps the doctors to decide on the most appropriate treatment.
Cancer can spread in the body, either in the bloodstream or through the lymphatic system. The lymphatic system is part of the body’s defence against infection and disease. It is made up of a network of lymph nodes connected by fine ducts containing lymph fluid. Your doctors will usually check the nearby lymph nodes when staging your cancer.
The cancer only affects the anus and is smaller than 2 cm (¾in) in size. It has not begun to spread into the sphincter muscle.
The cancer is bigger than 2 cm (¾in) in size, but hasn't spread into nearby lymph nodes or to other parts of the body.
The cancer has spread to the lymph nodes near the rectum, or to nearby organs such as the bladder or vagina.
The cancer has spread to lymph nodes in the groin and pelvis, or to lymph nodes close to the anus, as well as nearby organs such as the bladder or vagina.
The cancer has spread to lymph nodes in the abdomen or to other parts of the body, such as the liver.
A different staging system called the TNM staging system is sometimes used instead of the number system described above.
This system is more complex and can give more precise information about the tumour stage.
If the cancer comes back after initial treatment, it is known as recurrent cancer.
The National Institute for Health and Clinical Excellence (NICE) recommends that people with an anal cancer are treated by a specialist team. These teams aren't available in all hospitals, so you may have to travel to another hospital for your treatment.
The main type of treatment for anal cancer is a combination of radiotherapy and chemotherapy. The two treatments are normally given at the same time (chemo-
Surgery may be used to treat small anal tumours or be used in combination with chemotherapy or radiotherapy for advanced anal cancer. Surgery may be used for small tumours. It can also be used if your treatment doesn't completely get rid of the cancer, or if there are signs that the cancer has returned. Sometimes it’s used if radiotherapy isn’t appropriate, for example if you’ve had radiotherapy to the area before. Occasionally it’s used to relieve symptoms before treatment with chemo-
The majority of patients treated for anal cancer will not need a colostomy. If the tumour does not respond completely to combination therapy, if it recurs after treatment, or if it is an unusual type, removal of the rectum and anus and creation of a colostomy may be necessary. This operation is known as an an abdomino-
It's not unusual to have side effects for a time following treatment for anal cancer. These may include feeling bloated, having wind, diarrhoea and occasional incontinence. These side effects can be distressing but are usually temporary and improve over several months. Your doctor, nurse or dietitian will be able to give you advice about how to manage any side effects.
You will be followed up for between 5-
Your first port of call is usually your own GP who will be able to assess you symptoms and decide if a referral to a colorectal specialist is appropriate.
Anal cancers are unusual tumours arising from the skin or mucosa of the anal canal. As with most cancers, early detection is associated with excellent survival. Most tumours are well treated with combination chemotherapy and radiotherapy. Recurrences may occur but often can be treated successfully. Follow the recommended screening examinations for anal and colorectal cancer and consult your doctor early if you develop any of the symptoms listed above.
If you have any questions about anal cancer or other colorectal issues, your own GP is often the best first port of call.
If appropriate, they will be able to arrange a referral to a colorectal specialist centre such as the Glasgow Colorectal Centre.