Anal cancer

The anus, also known as the anal canal, is the last part of the bowel, connecting the lower end of the rectum to the outside of the body. It is approximately three cm long and surrounded by muscles called the anal sphincter, which help control bowel movements.

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Anal cancer develops when abnormal cells in the anal lining grow uncontrollably. The most common type is squamous cell carcinoma. When cancerous cells remain on the surface and have not yet invaded deeper layers, this is known as anal intraepithelial neoplasia (AIN), or high-grade dysplasia.

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Anal cancer is rare but slightly more common in women than men. The primary risk factor for anal cancer is infection with the human papillomavirus (HPV). Other risk factors include:

• Smoking

• Impaired immunity (such as HIV or immunosuppressive medication following an organ transplant)

• Ageing: the risk increases with age

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Symptoms of anal cancer

Early detection significantly improves survival rates. Some of the common symptoms of anal cancer include:

• Bleeding from the anus

• Pain, irritation, or persistent itching around the anus

• Change in bowel habit

• A lump at the anus

• Unusual discharge from the anus

 

These symptoms are common and are often due to non-cancerous conditions, such as haemorrhoids or anal fissures. However, if you experience these symptoms, you should seek medical advice for further investigation.

 

How is anal cancer diagnosed?

Your consultant will:

• Take a full medical history and discuss your symptoms

• Perform a clinical examination, which may include:

  • Rigid sigmoidoscopy – a short camera examination of the rectum and anal canal

  • Proctoscopy – a closer examination of the anal canal

 

Further tests may be required to confirm the diagnosis:

• Examination under anaesthetic (EUA) – allows a detailed examination and biopsy of suspicious tissue

• CT and MRI scans – help assess the extent of the disease

• PET scan – occasionally used if there are concerns about cancer spread

 

Treatment for anal cancer

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• If chemoradiotherapy does not completely eradicate the cancer, surgery may be required

• If the cancer is large, a colostomy (temporary or permanent) may be needed before starting chemoradiotherapy

• Advanced cases may require removal of the entire anus, leading to a permanent colostomy