Anal cancer, or cancer of the anus, is a rare type of cancer that affects the very end of the large bowel (large intestine).
Fewer than 1,200 people are diagnosed with anal cancer each year in the UK.
Signs and symptoms of anal cancer
The symptoms of anal cancer are often similar to more common and less serious conditions affecting the anus, such as haemorrhoids (piles) and small tears (anal fissures). Some people with anal cancer don't have any symptoms.
Symptoms of anal cancer can include:
itching and pain around the anus
small lumps around the anus
a discharge of mucus from the anus
loss of bowel control (bowel incontinence)
You should see your GP if you develop any of these symptoms. While they are unlikely to be caused by anal cancer, it is best to get them checked out.
What causes anal cancer?
The exact cause of anal cancer is unknown, although a number of factors can increase your risk of developing the condition:
infection with human papilloma virus (HPV) – a common and usually harmless group of viruses spread through sexual contact, which can affect the moist membranes lining your body
having anal sex or having many sexual partners – possibly because this increases your risk of HPV
having a history of cervical, vaginal or vulval cancer
having a weakened immune system, for example if you have HIV
Your risk of developing anal cancer increases as you get older, with half of all cases diagnosed in people aged 65 or over. The condition is also slightly more common in women than men.
Diagnosing anal cancer
If you see your GP with symptoms that could indicate anal cancer, they will usually ask about your symptoms and carry out some examinations.
This may involve feeling your abdomen (tummy) and carrying out arectal examination. A rectal examination involves your doctor inserting a gloved finger into your bottom so they can feel any abnormalities.
If they think further tests are necessary, your GP will refer you to hospital. At the hospital, a number of different tests may be carried out to check for anal cancer and rule out other conditions.
Some of the tests you may have include:
a sigmoidoscopy – where a thin, flexible tube with a small camera and light is inserted into your bottom to check for any abnormalities
a proctoscopy – where the inside of your rectum is examined using a hollow tube instrument with a light on the end
a biopsy – where a small tissue sample is removed from your anus during a sigmoidoscopy or proctoscopy so it can be examined in a laboratory
If these tests suggest you have anal cancer, scans may be carried out to check whether the cancer has spread. Once these are complete, your doctors will be able to 'stage' the cancer. This means giving it a score to describe how large it is and how far it has spread.
How anal cancer is treated
If you are diagnosed with anal cancer, you will be cared for by a multidisciplinary team. This is a team of different specialists who work together to provide the best treatment and care.
The main treatments used for anal cancer are:
chemoradiation – a combination of chemotherapy andradiotherapy
surgery – to remove a tumour or a larger section of bowel
In a small proportion of people where the cancer has spread and cannot be cured, chemotherapy alone may be considered to help relieve symptoms (known as palliative care).
Chemoradiation is a treatment that involves a combination of chemotherapy (cancer-killing medication) and radiotherapy (where radiation is used to kill cancer cells). It is currently the most effective treatment for anal cancer.
Chemotherapy for anal cancer is usually given in two sessions, lasting from Monday to Friday, with a four-week gap between the sessions. You will not usually need to stay in hospital during the weeks where treatment is given.
In many cases, part of the chemotherapy is delivered through a small tube (a peripherally inserted central catheter or PICC) in your arm, which stays in for the duration of treatment. This tube allows you to avoid being admitted to hospital for treatment over the two sessions. However you will be attached to a small plastic pump, which you will take home with you.
A few hospitals now offer tablet chemotherapy for anal cancer, which avoids the need for the pump and PICC.
Radiotherapy is usually given in short sessions, once a day from Monday to Friday, with a break at weekends. This is usually done for five to six weeks. You won't need to stay in hospital for these appointments. To prepare for radiotherapy, additional scans will be required.
Both chemotherapy and radiotherapy often cause significant side effects, including:
sore skin around the anus
sore skin around the penis and scrotum in men or vulva in women
hair loss (limited hair loss from the head but total loss from the pubic area)
These side effects are usually temporary, but there is also a risk of longer-term impacts, such as infertility. If you are concerned about the potential side effects of treatment, you should discuss these with your care team before treatment begins.
Other possible long-term side effects can include:
chronic (long-term) diarrhoea
a desire to open the bowels with little notice
vaginal pain when having sex
dry and itchy skin around the groin and anus
bleeding from the anus, rectum, vagina or bladder
You should inform your doctor if you develop any of these symptoms, so that they can be investigated and treated appropriately.
Surgery is used less commonly than chemoradiation for anal cancer. It is usually only considered if the tumour is small and can be removed easily, or if chemoradiation has been ineffective.
If the tumour is very small and clearly defined, it may be cut out during a procedure called a local excision. This is a relatively simple procedure, carried out under general anaesthetic, that usually only requires you to stay in hospital for a few days.
If chemoradiation has been unsuccessful, or the cancer has returned after treatment, a more complex operation called an abdominoperineal resection may be recommended. As with a local excision, this operation is carried out under general anaesthetic.
An abdominoperineal resection involves removing your anus, rectum, part of the colon, some surrounding muscle tissue and sometimes some of the surrounding lymph nodes (small glands that form part of the immune system), to reduce the risk of the cancer returning. You will usually need to stay in hospital for up to 10 days after this type of surgery.
During the operation, a permanent colostomy will also be formed to allow you to pass stools. A colostomy is where a section of the large intestine is diverted through an opening made in the abdomen called a stoma. The stoma is attached to a special pouch that will collect your stools after the operation.
Before and after the operation, you will usually see a specialist nurse who can offer support and advice to help you adapt to life with a colostomy. Adjusting to life with a colostomy can be challenging, but most people become accustomed to it over time.
After your course of treatment ends, you will need to have regular follow-up appointments to monitor your recovery and check for any signs of the cancer returning.
These appointments will start off being every few weeks or months, but will become gradually less frequent over time.
The outlook for anal cancer depends on how advanced it is when you are diagnosed, although it is generally better than for many other types of cancer as chemoradiation is often very effective.
Overall, 60-75% of people with anal cancer will live at least five years after diagnosis, and many will live much longer than this.
There are about 300 deaths from anal cancer each year in the UK.
Want to know more?
Cancer Research UK: anal cancer
Macmillan: anal cancer