Medical experts are not sure what causes anal cancer. However, the following are considered as possible risk factors:
- HPV (human papilloma virus) – some types of HPV are closely linked to anal cancer. Approximately 80% of patients with anal cancer are infected in the anal area with a HPV.
- Sexual partner numbers – this is also linked to HPV. The more sexual partners somebody has (or has had) the higher are the chances of being infected with HPV, which is closely linked to anal cancer risk.
- Receptive anal intercourse – both men and women who receive anal intercourse have a higher risk of developing anal cancer. HIV-positive men who have sex with men are up to 90 times more likely than the general population to develop anal cancer.
- Other cancers – women who have had vaginal or cervical cancer and men who have had penile cancer are at higher risk of developing anal cancer. This is also linked to HPV infection.
- Age – the older somebody is the higher is his/her risk of developing anal cancer. In fact, this is the case with most cancers.
- A weak immune system – people with a weakened immune system have a higher risk of developing anal cancer. This may include people with HIV/AIDS, patients who have had transplants and are taking immunosuppressant medications.
- Smoking – smokers are significantly more likely to develop anal cancer compared to non-smokers. In fact, smoking raises the risk of developing several cancers.
- Benign anal lesions – IBD (irritable bowel disease), haemorrhoids, fistulae or cicatrices. Inflammation resulting from benign anal lesions may increase a person’s risk of developing anal cancer.