Oral sex and can­cer: we need to do more than just talk about it

The Irish Times - Tuesday - Health - - Health Lifestyle - Muiris Hous­ton

Vac­ci­na­tion rates against the hu­man pa­pil­loma virus (HPV) have dropped dra­mat­i­cally as a re­sult of a cam­paign by so called anti-vaxxers. While their mo­ti­va­tion is multi-pronged, it has been sug­gested that one group, the re­li­gious right – es­pe­cially in the US – have adopted an anti HPV stance in the be­lief that vac­ci­nat­ing 12 and 13 year olds (to pre­vent a sex­u­ally trans­mit­ted in­fec­tion) en­cour­ages pre­ma­ture sex­ual ac­tiv­ity.

In­tro­duced in the Repub­lic in 2010 on the rec­om­men­da­tion of the World Health Or­gan­i­sa­tion, HPV vac­ci­na­tion is pri­mar­ily aimed at pre­vent­ing can­cer of the cervix. Al­most ev­ery case of cer­vi­cal can­cer – about 99 per cent – is es­ti­mated to be caused by per­sis­tent in­fec­tion with cer­tain strains of HPV.

Less prom­i­nent in the global de­bate about HPV has been its as­so­ci­a­tion with oral can­cer. To­bacco and al­co­hol are tra­di­tion­ally seen as the main risk fac­tors for oral can­cer but there is now over­whelm­ing ev­i­dence that HPV plays a causal role in some types of the dis­ease. For ex­am­ple, Canada, Den­mark, the Nether­lands, Nor­way, Swe­den, the US and the UK have wit­nessed in­creas­ing in­ci­dence of oropha­ryn­geal and oral cav­ity can­cers de­spite de­clines in smok­ing rates since the 1980s.

But this link flew be­neath the radar un­til 2013 when the ac­tor Michael Dou­glas dis­closed in an in­ter­view with the Guardian news­pa­per that his throat can­cer was “caused by HPV which ac­tu­ally comes about from cun­nilin­gus”.

As a re­sult, the link be­tween HPV and oral can­cer and the trans­mis­sion of HPV via oral sex re­ceived ex­ten­sive me­dia cov­er­age.

Anti-vac­cine groups

The main risk fac­tors for oral in­fec­tion with HPV are thought to be a greater num­ber of oral sex part­ners, gen­er­at­ing greater ex­po­sure to the virus. This is an ar­gu­ment for vac­ci­nat­ing boys as well as girls as a pre­ven­tive health mea­sure; how­ever the pro­posal has re­in­forced the fears of re­li­giously-mo­ti­vated anti-vac­cine groups.

De­spite a tem­po­rary surge in in­ter­est at the time of the Dou­glas com­ment, aware­ness of the signs and risk fac­tors for head and neck can­cer is poor and the ma­jor­ity of oral can­cers con­tinue to be di­ag­nosed at an ad­vanced stage. In one US pop­u­la­tion-based on­line sur­vey, HPV was recog­nised as a com­mon risk fac­tor for mouth and throat can­cer by fewer than 1 per cent of par­tic­i­pants, and even when prompted ex­plic­itly about the link, just 13 per cent said they had heard of the as­so­ci­a­tion.

Ex­perts be­lieve HPV may play a part in the de­vel­op­ment of some oral can­cers. It seems the virus can lie dor­mant for months or years be­fore caus­ing cell changes that, in some peo­ple, may de­velop into can­cer.

Sex­ual be­hav­iour coun­selling

A re­cent re­view in the Post­grad­u­ate Med­i­cal Jour­nal set out to de­ter­mine whether there is strong ev­i­dence to cor­re­late oral sex with head and neck can­cers, which in turn would jus­tify sex­ual be­hav­iour coun­selling for pa­tients.

The au­thors re­port a four times higher preva­lence of oro-gen­i­tal sex in pa­tients with HPV-pos­i­tive oral can­cers than in HPV-neg­a­tive pa­tients. In ad­di­tion, a meta-analysis of sex­ual be­hav­iours and head and

The main risk fac­tors for oral in­fec­tion with HPV are thought to be a greater num­ber of oral sex part­ners, gen­er­at­ing greater ex­po­sure to the virus

neck can­cers sug­gested an in­creased risk of head and neck can­cers among peo­ple with a higher num­ber of oral sex part­ners.

Sex­ual be­hav­iours like hav­ing un­pro­tected oral sex, prac­tis­ing oro-anal sex or hav­ing mul­ti­ple sex­ual part­ners play an im­por­tant role in HPV trans­mis­sion and in­fec­tion that may re­sult in HPV-associated head and neck can­cer, “which is an emerg­ing epi­demic”, they con­clude.

“Pa­tients are more likely to be younger, well-ed­u­cated males from higher so­cio-eco­nomic back­grounds. There is a need for proper doc­u­men­ta­tion and for coun­selling of pa­tients re­gard­ing sex­ual be­hav­iours to pre­vent the spread of HPV in­fec­tion and associated can­cers.”

But a cou­ple of im­por­tant re­search ques­tions re­main to be an­swered: why do women have a lower in­ci­dence of HPV-re­lated oropha­ryn­geal car­ci­noma?

And which spe­cific sex­ual be­hav­iours are most likely to lead to HPV trans­mis­sion?

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