Anal Cancer: Symptoms and Risk Factors

Anal cancer is when malignant cancer cells form in the tissue in the anus. Anal cancer usually occurs in two areas: where the anal canal meets the rectum or in the skin just outside the anal opening.

Over 80% of anal cancer cases are linked to infection of Human Papilloma Virus (HPV). HPV is a very common infection usually transmitted from different forms of sexual contact. Depending on the type of HPV, the virus can affect different parts of the human body, which include the anus, cervix, vagina, penis, throat and inside of the mouth.  Anal cancer is caused by HPV16 and HPV18.


Early stages of anal cancer often do not cause any symptoms or only cause non-specific symptoms, which can be commonly found in other illnesses.

Anal cancer symptoms may include:

  • Blood in stool or on the toilet paper
  • Bleeding from the rectum. Nearly 50% of individuals diagnosed with anal cancer have had symptoms of rectal bleeding or blood in their stool.
  • Bowel changes such as difficulty controlling bowel movements
  • Discharge of mucus from the anus
  • Pain, itching or discomfort in the area around the anus
  • Feeling full, discomfort or pain in the rectum
  • Feeling a lump near the edge of the anus
  • Ulcers around the anus

If you experience any of these symptoms or have concerns, please contact your general practitioner (GP).

Risk factors

Risk factors for anal cancer include:

  • Infection of Human Papilloma Virus (HPV), which is linked to over 80% of anal cancer cases
  • Having a weakened immune system. Your immune system protects you from possible infections and diseases. A weakened immune system makes the individual at greater risk of developing illness. This can be caused by having Human Immunodeficiency Virus (HIV), organ transplantation or autoimmune diseases.
  • Older age
  • Smoking
  • Having anal or genital warts
  • Having unprotected sex
  • Having multiple sex partners
  • Men who have had sex with other men
  • Women who have a medical history of cervical, vaginal or vulval cancer.

Learn more about anal cancer

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