Anal cancer

Anal cancer is a rare type of cancer that affects the very end of the large bowel.

Less than 1,200 people are diagnosed with cancer of the anus each year in the UK.

Symptoms of anal cancer

The symptoms of anal cancer are often similar to more common and less serious conditions affecting the anus, such as piles (haemorrhoids) and anal fissures (small tears or sores).

Symptoms of anal cancer can include:

• bleeding from the bottom (rectal bleeding)
• itching and pain around the anus
• small lumps around the anus
• a discharge of mucus from the anus
• loss of bowel control (bowel incontinence)

However, some people with anal cancer don't have any symptoms. 

See your GP if you develop any of the above symptoms. While they're unlikely to be caused by anal cancer, it's best to get them checked out.

Diagnosing anal cancer

Your GP will usually ask about your symptoms and carry out some examinations.

They may feel your tummy and carry out a rectal examination. This involves your doctor inserting a gloved finger into your bottom so they can feel any abnormalities. Your GP will refer you to hospital if they think further tests are necessary. 

The National Institute for Health and Care Excellence (NICE) recommends in its 2015 guidelines that GPs should consider referring someone with an unexplained anal lump or anal ulcer. The person should receive an appointment within two weeks.

If you're referred to 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
• proctoscopy – where the inside of your rectum is examined using a hollow tube-like instrument (proctoscope) with a light on the end
• biopsy – where a small tissue sample is removed from your anus during a sigmoidoscopy or proctoscopy so it can be examined in a laboratory under a microscope 

If these tests suggest you have anal cancer, you may have some scans 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.

You can read more about the stages of anal cancer on the Cancer Research UK website.

How anal cancer is treated

If you're diagnosed with anal cancer, you'll 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 and radiotherapy
• surgery – to remove a tumour or a larger section of bowel

In cases where the cancer has spread and can't be cured, chemotherapy alone may be considered to help relieve symptoms. This is known as palliative care.

The main treatments are described in more detail below.

Chemoradiation

Chemoradiation is a treatment that combines chemotherapy (cancer-killing medication) and radiotherapy (where radiation is used to kill cancer cells). It's currently the most effective treatment for anal cancer. You don't usually need to stay in hospital when you're having chemoradiation.

Chemotherapy for anal cancer is usually given in two cycles, each lasting four to five days, with a four-week gap between the cycles. In many cases, part of the chemotherapy is delivered through a small tube called a peripherally inserted central catheter (PICC) in your arm, which can stay in place until your treatment has finished.

The tube means you don't need to stay in hospital during each of the cycles of chemotherapy. However, you'll be attached to a small plastic pump, which you take home with you.

A few hospitals now offer tablet chemotherapy for anal cancer, which avoids the need for the pump and PICC.

Read more about how chemotherapy is carried out.

Radiotherapy is usually given in short sessions, once a day from Monday to Friday, with a break at weekends. This is usually carried out for five to six weeks. To prepare for radiotherapy, additional scans will be required.

Read more about how radiotherapy is carried out.

Both chemotherapy and radiotherapy often cause significant side effects, including:

• tiredness
• 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
• feeling sick
• diarrhoea

These side effects are usually temporary, but there's also a risk of longer-term problems, such as infertility. If you're concerned about the potential side effects of treatment, you should discuss this with your care team before treatment begins. 

Other possible long-term side effects can include:

• bowel control problems
• long-term (chronic) diarrhoea
• erectile dysfunction
• vaginal pain when having sex
• dry and itchy skin around the groin and anus
• bleeding from the anus, rectum, vagina or bladder

Tell your doctor if you develop any of these symptoms so they can be investigated and treated.

Surgery

Surgery is a less common treatment option for anal cancer. It's usually only considered if the tumour is small and can be easily removed, or if chemoradiation hasn't worked.

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 a stay in hospital of 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'll 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. This 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'll 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.

Read more about living with a colostomy.

Follow-up

After your course of treatment ends, you'll need to have regular follow-up appointments to monitor your recovery and check for any signs of the cancer returning.

To start with, these appointments will be every few weeks or months, but they'll gradually become less frequent over time.

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. These include:

• 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 lots of sexual partners – possibly because this increases your risk of developing HPV
• having a history of cervical, vaginal or vulval cancer
• smoking
• 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.

Outlook

The outlook for anal cancer depends on how advanced the condition is when it's diagnosed. The earlier it's diagnosed, the better the outlook.

Compared with many other types of cancer, the outlook for anal cancer is generally better because treatment is often very effective. Around 66 out of 100 people (66%) 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.

Further information about anal cancer

• Cancer Research UK: anal cancer
• Macmillan: anal cancer