What causes anal cancer?

Human papillomavirus, or HPV, can infect skin and lining tissues around the anus. Most HPV infections do not become cancer, but an infection that persists can alter cells over time. Other factors may affect risk, including a weakened immune system, previous HPV-related disease, smoking and a history of anal irritation or abnormal cell changes. Having a risk factor does not mean cancer will develop, and anal cancer can occur without a clear explanation.

Arrange an assessment for bleeding, a persistent lump, pain, itching, discharge or a change in bowel control. A clinician may inspect the area, perform a digital examination and arrange further testing if an abnormal area is found. Ask about HPV vaccination, smoking support and follow-up if you have had abnormal anal cells or a weakened immune system. Do not assume symptoms are haemorrhoids without an examination.

Seek urgent help for heavy bleeding, severe pain, inability to pass stool, fever with worsening swelling, or faintness. Book a prompt appointment for any persistent anal lump, bleeding or change in bowel control, especially when it is new or worsening.

Could HPV or another condition explain my symptoms? Do I need an examination or biopsy? Would vaccination or immune-system care be relevant? What changes should I report quickly?