What is anal cancer?

Anal cancer is a cancer that affects the tissues of the anus. Most anal cancers are squamous cell carcinomas (SCC). Squamous cells are a type of cell that line the surface of the anal canal.

Some anal cancers are adenocarcinomas of the anus, a cancer of the cells that make the mucus that helps the stools (faeces) move smoothly out of the anus. In rarer cases, some SCCs affect the skin outside the anus (perianal skin cancers). 

Anal cancer is a rare cancer. It is estimated that more than 600 people were diagnosed with anal cancer in 2023. The average age at diagnosis is 67 years old.


Anal cancer signs and symptoms

The symptoms can include:

  • lumps around the anus or in the groin
  • ulcers around the anus
  • pain, discomfort, or itching around the anus
  • blood or mucus in stools (faeces) from the anus
  • difficulty controlling your bowel movements
  • a feeling of fullness, pain, or discomfort in the rectum.

These symptoms may be caused by other conditions such as haemorrhoids or tears in the anal canal. However, if symptoms persist, see your doctor for a check-up.


Causes of anal cancer

The most common cause of anal cancer is the human papilloma virus (HPV), accounting for around 90 per cent of cases.

  • having diseases such as chlamydia, anal warts and AIDS/HIV
  • women who have already had cervical, vulval or vaginal cancer or a history of abnormal cells in the cervix, vulva or vagina
  • people who have anal intercourse may have an increased risk of anal cancer possibly due to an increased risk of HPV infection
  • people with weakened immune systems
  • smoking tobacco.

Diagnosis of anal cancer

Tests to diagnose anal cancer may include:

Physical examination

The doctor will conduct a digital anorectal examination (DARE) by inserting a gloved finger into your anus to check for any swelling or lumps. 

Biopsy

Your doctor will insert a narrow instrument called a sigmoidoscope or colonoscope into your anus to see the lining of the anal canal and to take a tissue sample (biopsy) that will be sent to a laboratory for testing. 

If anal cancer is detected, you may have scans to see if the cancer has spread to other parts of your body. These may include:

MRI

A magnetic resonance imaging (MRI) scan uses a powerful magnet and radio waves to create 3D pictures of areas inside the body. Sometimes dye will be injected into a vein to make the pictures clearer.

Endorectal ultrasound

An ultrasound probe is inserted through the anus into your rectum. This can be uncomfortable but is usually not painful. The probe sends out soundwaves that echo when they meet something dense, like a tumour, and images are projected onto a computer screen.

CT scan

A computerised tomography (CT) scan uses x-rays and a computer to create a detailed picture of an area inside the body. Before the scan, dye may be injected into a vein to make the pictures clearer.

After a diagnosis of anal cancer  

After a diagnosis of anal cancer, you may feel upset, confused, anxious or upset. These are normal reactions. Talk about your treatment options with your doctor, family and friends. See as much information as you need.  

Anal cancer is rare so your specialist will probably recommend treatment in a specialist centre by a range of health professionals.  


Treatment for anal cancer

Anal cancer is rare so it is usually recommended that you be treated in a specialised centre by a multidisciplinary team.

Staging

Staging indicates the size of the cancer and how far it has spread and helps your doctors plan the best treatment.

Most people with anal cancer receive a combination of chemotherapy and radiation therapy (radiotherapy) treatments at the same time, called chemoradiation. Surgery may also be used. This will depend on the type and stage of anal cancer you have.

Radiation therapy (radiotherapy)

Radiotherapy, the use of x-rays to kill or injure cancer cells, is given either externally, where a machine directs radiation at the cancer and surrounding tissue; or from inside the body (brachytherapy), where radioactive material is put in thin tubes and placed near the cancer internally. 

Radiotherapy to this area of the body may cause temporary or permanent infertility in both men and women. Therefore, if you are concerned about how treatment will affect your fertility, it is important to raise your concerns with your treatment team before treatment commences.

Chemotherapy

Chemotherapy can be used alone or combined with radiation therapy (chemoradiation) to treat anal cancer. Chemotherapy is usually given as a drug that is injected into a vein (intravenously).

For chemoradiation treatment, radiation therapy starts the same day as the first cycle of chemotherapy commences. Radiation therapy is delivered every week day for about five to six weeks. Side effects have been greatly reduced since the introduction a focused radiotherapy called intensity modulated RT (IMRT).

Surgery

Surgery may be used to treat anal cancer if it is in the early stages, or hasn't completely gone after chemoradiation, or it comes back after treatment (recurs). The type of surgery will depend on the size and type of the cancer. An early stage tumour that doesn't affect the muscles around the anus may be operable as a local resection, where the affected area is removed.

A larger operation, called an abdomino-perineal resection, may be required if the cancer is present after initial treatment or if you are unable to have chemoradiation. This procedure involves the removal of the anus, rectum and part of the colon, and possibly lymph nodes near the anus and groin. If you have this procedure, you will have a permanent stoma (colostomy). Before and after your surgery, a stoma nurse will assist you in what is involved in living with a colostomy.

Palliative care

In some cases of anal cancer, your medical team may talk to you about palliative care. Palliative care aims to improve your quality of life by alleviating symptoms of cancer.

As well as slowing the spread of anal cancer, palliative treatment can relieve pain and help manage other symptoms. Treatment may include radiotherapy, chemotherapy or other drug therapies.

Side effects

Treatment for anal cancer and even the cancer itself, can cause side effects. The types and severity of any side effects you may experience will depend on the type of treatment you have and may vary from person to person. Most side effects are temporary and can be prevented, reduced or managed.   

Some of the side effects you may experience include:  

  • fatigue 
  • appetite loss and nausea and vomiting  
  • mouth problems  
  • bowel changes such as diarrhoea, painful or urgent bowel movements  
  • pain in the anal area 
  • increased risk of infection 
  • skin changes such as itching, peeling or blistering around the anus, groin or genital area 
  • changes to body image and sexuality  
  • loss of pubic hair 
  • changes to fertility.  

Talk to your health care team about any changes you experience during and after treatment.   

Treatment Team

Depending on your treatment, your treatment team may consist of a number of different health professionals, such as:
  • GP (General Practitioner) - looks after your general health and works with your specialists to coordinate treatment.
  • Radiation oncologist - prescribes and coordinates radiation therapy treatment.
  • Medical oncologist - prescribes and coordinates the course of chemotherapy.
  • Cancer nurse - assists with treatment and provides information and support throughout your treatment.
  • Stoma nurses- provide information about surgery and can provide you with support to adjust to life with a temporary or permanent stoma.
  • Sexual therapist- qualified counsellor who has been trained to help patients manage sexual concerns.
  • Other allied health professionals - such as social workers, pharmacists, and counsellors
  • Surgeon- surgically removes tumours and performs some biopsies..


Preventing anal cancer

There are no proven measures to prevent anal cancer.

However, it is possible to reduce some of the risks, in particular HPV infection by using one of the HPV vaccines that are now available.  


Prognosis for anal cancer

It is not possible for a doctor to predict the exact course of a disease, as it will depend on each person's individual circumstances. However, your doctor may give you a prognosis, the likely outcome of the disease, based on the type of anal cancer you have, the test results, the rate of tumour growth, as well as your age, fitness and medical history.

The most common types of anal cancer have a very good long-term prognosis, especially if the cancer is found early.