Causes and risk factors of anal cancer
There are some risk factors that can increase your chance of developing anal cancer. Most anal cancers are caused by the human papillomavirus (HPV).
Risk factors can increase the chance of a person developing a certain type of cancer. Having one or more risk factors does not mean you will definitely get anal cancer. If you do not have any risk factors, it does not mean you will not get anal cancer.
Most anal cancers are caused by the human papillomavirus (HPV). Almost everyone will have HPV at some point. But not everyone will develop anal cancer.
HPV is a virus that is linked to different cancers, including anal cancer. It is a common infection that is passed on through sexual contact. Most people have HPV at some point and never know they have had it.
There are over 100 types of HPV. Some types are more likely to cause cancer than others. Some types may cause genital warts. Using a condom can help reduce the risk of getting HPV.
Usually, our immune system gets rid of the HPV infection without it causing any problems. But a small number of HPV infections may lead to cancer developing.
We have more information about HPV and cancer.
The immune system is part of the body’s defence against infections. Anal cancer is more common in people who have a lower immunity. This includes:
- people with HIV
- people taking medicines to suppress their immune system after an organ transplant.
Having lots of sexual partners increases the chance of getting HPV. But even a person with only one partner can have this virus.
Having anal sex increases the risk of anal cancer. But HPV is passed on easily through sexual contact. So people may develop anal cancer even if they have never had anal sex.
This is when abnormal cells develop in the skin just inside or outside the anus. This is usually caused by HPV.
Most people who have AIN have no symptoms. But symptoms can include:
- skin changes around the anus
- bleeding (but this is rare).
If AIN is left untreated, it can develop into anal cancer over many years.
Below is a sample of the sources used in our anal cancer information. If you would like more information about the sources we use, please contact us at firstname.lastname@example.org
R Glynne-Jones, PJ Nilson, C Aschele et al. ESMO-ESSO-ESTRO clinical practice guidelines for diagnosis, treatment and follow up for anal cancer. July 2014. European Society of Medical Oncology. Available from www.esmo.org/Guidelines/Gastrointestinal-Cancers/Anal-Cancer (accessed October 2019).
Association of Coloproctology of Great Britain & Ireland (ACPGBI). Volume 19. Issue S1. Guidelines for the management of cancer of the colon, rectum and anus. 2017. Available from: www.onlinelibrary.wiley.com/toc/14631318/19/S1 (accessed October 2019).
R Muirhead, RA Adams, DC Gilbert et al. National guidance for IMRT in anal cancer. December 2016 (accessed October 2019).
D Ryan, C Willett et al. Clinical features, staging, and treatment of anal cancer. Uptodate 2019. Available at www.uptodate.com/contents/clinical-features-staging-and-treatment-of-anal-cancer (accessed October 2019).
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.
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