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Anal Cancer

Anal cancer starts in the anus, the opening at the end of the bowel. It is rare, but around 9 in 10 cases are linked to HPV, and rates in the UK have risen sharply since the 1970s.

~90%of anal cancers in the UK are attributable to HPV

Attributable to HPV. Source: (Parkin, 2011)

What it is

The anus is the short canal at the end of the bowel that is controlled by muscles called sphincters. Like the cervix, the anal canal has a transformation zone where two types of cells meet, and this is where most anal cancers start.

Most anal cancers are squamous cell carcinomas. Anal cancer is different from bowel cancer. It behaves differently and is usually treated with a combination of chemotherapy and radiotherapy rather than surgery.

Symptoms

  • Bleeding from the bottom, or blood in your poo
  • Itching, pain, swelling or a feeling of pressure around the anus
  • Small lumps around or inside the anus
  • A discharge of mucus or pus from the anus
  • Difficulty controlling your bowels (incontinence)
  • Changes in your bowel habits, such as severe constipation or feeling you need to go when you don’t
  • Changes to piles you already have
  • Swollen glands in the groin

Early anal cancer often causes no symptoms.

These symptoms are often caused by more common problems such as piles (haemorrhoids). But don’t feel embarrassed to see your GP, especially if symptoms don’t go away.

Causes

Most anal cancers are caused by a long-lasting infection with high-risk HPV, mainly HPV16. HPV can reach the anus through any genital skin-to-skin contact, including anal sex, and through sharing sex toys. Most people with HPV never develop anal cancer.

Statistics

1,700people diagnosed in the UK each year
530deaths from anal cancer in the UK each year
52%survive for 10 years or more
91%of cases are considered preventable

About two in three UK cases (around 1,100 a year) are in women. Anal cancer rates have almost doubled since the early 1990s. Source: Cancer Research UK.

Risk factors

  • HPV infection, the main cause
  • A weakened immune system, especially HIV, or medicines taken after an organ transplant
  • Smoking
  • Receptive anal sex
  • Having had cervical, vaginal or vulval cancer, or pre-cancerous changes in those areas
  • Older age. The NHS notes risk is higher over the age of 75

Groups at higher risk of HPV include men who have sex with men, some trans people, sex workers and people living with HIV. Many of these groups can get the HPV vaccine free at sexual health clinics.

How it develops

HPV infects cells in the anal transformation zone in the same way it infects the cervix, using its E6 and E7 proteins to switch off the cell’s natural brakes on growth.

Over time, infected cells can develop abnormal changes called anal intraepithelial neoplasia (AIN), also called anal HSIL when the changes are high grade. These are not cancer, but some can progress to cancer over many years.

There is no NHS screening programme for anal cancer, so knowing the symptoms is important. Some specialist clinics monitor people at very high risk, such as people living with HIV.

Diagnosis and treatment

Your GP may examine you and refer you to a specialist, who may look inside the anus with a small camera and take a biopsy. Many causes of bleeding and discomfort are not cancer.

Anal cancer is usually treated with chemoradiotherapy, a combination of chemotherapy and radiotherapy, which often avoids the need for surgery. Surgery is sometimes used for very small cancers or if other treatment hasn’t worked.

Prevention

  • Get the HPV vaccine if you’re eligible. Men who have sex with men can get it free up to their 46th birthday at sexual health and HIV clinics.
  • Use condoms and dental dams for anal sex and oral-anal sex (rimming). They give partial protection.
  • Stop smoking.
  • Know the symptoms and see your GP early, especially if you have HIV or a history of cervical, vaginal or vulval cell changes.

Common misconceptions

"Only gay men get anal cancer."

More women than men are diagnosed with anal cancer in the UK each year. Men who have sex with men do have a higher risk, but anyone can be affected.

"You can only get anal cancer if you’ve had anal sex."

HPV can reach the anus through skin contact from the genitals, or through oral-anal sex. Anal sex increases exposure to HPV, but it isn’t needed.

"Bleeding from the bottom is just piles."

It usually is, but don’t assume. See your GP if bleeding, pain or lumps don’t go away.

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