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A new study by the International Agency for Research
on Cancer (IARC), in partnership with Costa Rican
investigators and the United States National Cancer
Institute (NCI), shows for the first time that the
vaccine against human papillomavirus (HPV) types 16
and 18, which is used to prevent cervical cancer,
also provides strong protection against oral HPV
infections, known to be associated with cancer of
the oropharynx and tonsils.
The study, conducted in Costa Rica and published in
the journal PLOS ONE, was initially designed to
evaluate the vaccine’s efficacy against cervical
cancer. It later included evaluation of the
vaccine’s efficacy at other anatomical sites,
including the oral cavity, where researchers
established that the vaccine reduces oral infections
with HPV 16 and 18 by more than 90%.
In 2004 and 2005, a total of 7466 healthy women aged
18–25 years received the HPV16/18 vaccine or
hepatitis A vaccine as control. A total of 5840
participants provided oral specimens, which were
used to evaluate the efficacy of the vaccine against
oral HPV infections. The vaccine trial showed that
the HPV16/18 vaccine reduced by 93% the prevalence
of or al HPV16/18 infections 4 years after
vaccination.
HPV is better known for causing cervical cancer,
which is the third most common cancer in women
worldwide, with an estimated 530 000 new cases and
275 000 deaths in 2008.
HPV types 16 and 18 are also associated with cancers
in a variety of other locations, including the
vulva, vagina, penis, anus, and oropharynx.
The estimated number of new cases of cancer of the
oropharynx (including the tonsils and the base of
the tongue) is approximately 85 000 per year in both
sexes worldwide, and men are 4 times more likely
than women to be affected.
However, the incidence of oropharyngeal cancer has
increased significantly in recent years in the USA
and Europe, particularly among men and in young
people.
“The vaccine seems to provide strong protection
against oral HPV infections with the viral types
that cause most cancers of the oropharynx,” said Dr
Rolando Herrero from IARC, lead author of the study.
“There are many aspects of the disease that we still
don’t understand, and we need more direct evidence
that the vaccine prevents oropharyngeal cancer, but
these results indicate that we may now have an
important tool for primary prevention of these in
creasingly common malignancies.”
Most oropharyngeal cancers have traditionally been
linked with heavy tobacco and alcohol consumption,
but 30% of oropharyngeal cancers worldwide are now
thought to be related to HPV infection , which is
linked to sexual practices, such as oral sex.
A recent study in the USA showed that over the past
20 years, the rate of HPV detection in oropharyngeal
tumour specimens increased from 16% to 70% , leading
that study’s authors to postulate that in the next
few decades in the USA there may be more cases of
HPV-related oropharyngeal cancer than HPV-related
cervical cancer.
“The results of our study demonstrated protection
against oral HPV infection in women. If similar
results are observed in men, vaccination of boys may
become
an important public health measure in areas where
oropharyngeal and other HPV-related cancers are
relatively common in men,” added Dr Herrero.
Last month, another IARC study in partnership with
NCI showed that antibodies to HPV16 could help
detect oropharyngeal cancer several years before the
clinical onset of the disease.
Dr Christopher Wild, Director of IARC, concluded
that “both these results show an exciting area of
research that will hopefully lend itself to public
health action and help reduce the burden of
HPV-induced cancers in the medium term.”
For more information
International Agency for Research on Cancer, IARC
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