HPV and Anal Cancer: How did I get it, am I infectious, and what does it mean?
We are delighted to share this blog written by Richard Turner, who is a Professor of Surgery in Hobart, Tasmania. He is an expert in anal neoplasia, has practised high-resolution anoscopy for decades and has published on the topic. He is currently on the executive committee of the International Anal Neoplasia Society (IANS).
HPV is extremely common and is responsible for most cases of anal pre-cancer (HSIL) and anal cancer.
This article explains how HPV leads to these conditions over time, how it is transmitted, whether it remains infectious, and what a diagnosis means for sexual activity and day-to-day life.
How did I get this?
Squamous cell carcinoma of the anus and its precursors (HSIL) are caused by a previous infection with the Human Papilloma Virus (HPV) in over 90% of cases.
There are over 100 different strains of HPV, about a dozen of which have the potential to lead to cancer, but HPV16 especially. The virus gets into the deeper layers of cells that line susceptible parts of our body (e.g. anus, penis, throat, cervix, vagina and vulva) through minor tears or micro-abrasions. Once there, these ‘oncogenic’ (cancer-causing) HPV strains integrate their DNA with our own cells and start to multiply with them. Over a number of years, this can cause the cells to grow abnormally (with ‘high-grade’ changes) and eventually become cancerous, spreading beyond their usual boundaries.
In most cases, this infection is transient – our immune system clears it. In a small percentage of people, it can hang around (as noted above). The reasons for this are not entirely clear, but we do know that people are at increased risk if they have a history of immune suppression due to HIV or organ transplantation.
Furthermore, the interval between the initial HPV infection and anal cancer is typically a few decades. Most people are infected in their 20s, when they are most sexually active, but the peak incidence of anal cancer occurs in the 60s. The intervening period is when the infected cells with high-grade changes are slowly mutating – thus the rationale for ‘nipping things in the bud’ with targeted treatments guided by high-resolution anoscopy (HRA). For more information about HRA, read our blog ‘What Do I Need to Know About HRA’.
Is this because of my multiple sexual partners and ‘varied’ sexual practices?
Strictly speaking, HPV is a sexually transmitted infection. This may lead patients to feel unclean, perhaps even blaming themselves for having brought it on through what some may consider ‘unwise’ sexual practices. However, compared to other STIs, HPV is highly infectious. Anyone who has been in intimate contact with others has probably been infected at some point. Sexual relations are a frenzy of fingers, tongues and genitals – and HPV can be easily transmitted by surface-to-surface contact, especially if there is minor trauma to the ‘receiving surface’.
Receptive anal intercourse (which obviously is nothing to feel guilty about) would therefore be the obvious way of acquiring HPV infection in the anus, but not the only way. A study from Tasmania showed that women who had been exposed to HPV in the vaginal area could infect their anus simply by the way they wiped themselves after going to the bathroom. (Simpson, Turner et.al. 2016, Cancer Epidemiology). For those who don’t have anal sex, it is possible that HPV is transmitted to the anus by simply trickling down from higher up.
Am I still infectious?
By the time someone develops anal cancer or precancer, the infection is burnt out, and the virus is usually no longer infectious. There is virtually zero risk of giving it to a partner at this late stage.
There is, of course, a chance of acquiring a new HPV infection if you are sexually active, so condoms may be a good idea if you are concerned about this. Some people also opt to receive the Gardasil vaccination, although this will not necessarily impact a pre-existing HPV-related abnormality.
So no more anal play for me, right?
If you have a diagnosis of anal HSIL, receptive anal sex or inserting toys will not make it worse – so you can and should continue to enjoy this if you wish. That said, you should take the usual precautions to avoid new sexually transmitted infections (you can discuss this further with your GP or sexual health doctor if you wish).
If you have had an anal biopsy (commonly after HRA), you should avoid anal play at least until any bleeding has stopped and until you have had a bowel movement. For bigger procedures, where the anal lining has been breached, you may have to wait slightly longer – please ask your surgeon about this. When you do resume anal activity, it is best to take things slowly at first – long foreplay, plenty of lube (you can never have too much), fingers or small toys first, etc.
If you have concerns about HPV, anal HSIL, or your risk of anal cancer, discussing these with your doctor can help clarify whether screening or further assessment is appropriate. Dr Marino is an LGBTQIA+ friendly colorectal surgeon in Melbourne with specialised training in high-resolution anoscopy and anal cancer screening, and accepts referrals via your GP.
