Risk factors of anal cancer

In the UK, about 1,100 people develop anal cancer each year. It is slightly more common in women than men. The exact cause in most people is still unknown. However, we know that certain things called risk factors can increase a person’s chances of developing it. Having one or more risk factors doesn’t mean you will definitely get anal cancer. Equally, if you don’t have any risk factors, it doesn’t mean you won’t get anal cancer.


Like most types of cancer, the risk of developing anal cancer increases as you get older.

Human papilloma virus (HPV)

Anal cancer is more likely to develop in people who’ve had a viral infection called the human papilloma virus (HPV). There are over 100 different types of HPV and only a few of them are linked to cancer. HPV is a very common infection – about 80% of us will have an HPV infection at some point. The risk of having the virus increases with the number of sexual partners you have. We have more information about HPV and cancer.

Sexual activity

People who have anal sex are more likely to develop anal cancer. This may be because they are more likely to have anal HPV. However, anal cancer can also develop in people who haven’t had anal sex or HPV.

Lowered immunity

The immune system is part of the body’s defence against infections and illnesses such as cancer. Anal cancer is more common in people who have a lowered immunity, such as people taking medicines to suppress their immune system after an organ transplant or people with conditions such as HIV. We have more information about low immunity.


Smoking tobacco increases the risk of developing anal cancer. Stopping smoking can help reduce the risk of developing cancer. We have more information about giving up smoking.

Back to Potential causes of cancer

Low immunity

People with low immunity are more likely to develop some types of cancer.

Human papilloma virus (HPV)

Human papilloma virus (or HPV) is a common infection. Some types of HPV can increase the risk of developing cancer.