Oral Sex linked to
Mouth Cancer
Oral sex can lead to oral tumours. That is the conclusion of
researchers who have proved what has long been suspected, that the
human papilloma virus can cause oral cancers.
The risk, thankfully, is tiny. Only around 1 in 10,000 people
develop oral tumours each year, and most cases are probably caused
by two other popular recreational pursuits: smoking and drinking.
The researchers are not recommending any changes in
behaviour.
The human papilloma virus (HPV), an extremely common sexually
transmitted infection, has long been known to cause cervical
cancers. Several small studies have suggested it also plays a role
in other cancers, including oral and anal cancers.
"There has been tremendous interest for years on whether it has a
role in other cancers. Many people were sceptical," says Raphael
Viscidi, a virologist at Johns Hopkins University School of
Medicine in Baltimore, Maryland, a member of the team that did the
latest work.
The researchers, working for the International Agency for Research
on Cancer in Lyon, France, compared 1670 patients who had oral
cancer with 1732 healthy volunteers. The participants lived in
Europe, Canada, Australia, Cuba and Sudan. HPV16, the strain seen
most commonly in cervical cancer, was found in most of the oral
cancers too.
Antibodies against HPV
The people with oral cancers containing the HPV16 strain were three
times as likely to report having had oral sex as those whose tumour
did not contain HPV16. There was no difference between men and
women in terms of how likely the virus was to be present in the
cancers. The researchers think both cunnilingus and fellatio can
infect people's mouths.
Patients with mouth cancer were also three times as likely to have
antibodies against HPV as the healthy controls. For cancers of the
back of the mouth, the link was even stronger.
The results prove the connection between HPV and oral cancer beyond
any reasonable doubt, Viscidi says. "This is a major study in terms
of its size," he says. "I think this will convince people."
Cancer specialist Newell Johnson of King's College London agrees.
"We have known for some time that there is a small but significant
group of people with oral cancer whose disease cannot be blamed on
decades of smoking and drinking, because they're too young," he
says.
"In this group there must be another factor, and HPV and oral sex
seems to be one likely explanation. This study provides the
strongest evidence yet that this is the case."
Cancer-causing strains
Genital HPV infections are common. At any one time, around a third
of 25-year-old women in the US are infected. It is thought that
only 10 per cent of infections involve cancer-causing strains, and
that 95 per cent of women will get rid of the infection within a
year. But even this does not explain why so few develop
cancer.
The latest findings could improve treatments of oral cancers. Many
scientists think that HPV infection must persist for tumours to
grow, so giving antiviral drugs to people with oral cancers caused
by the virus could improve their chances of recovery.
Prevention could soon be a possibility as well. Several research
groups are developing vaccines against HPV, intended to reduce the
250,000 deaths worldwide each year due to cervical cancer. It is
thought the vaccines would prevent oral infections as well as
genital infections.
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