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High-risk anal HPV infections persist in a significant proportion of HIV-negative MSM
Michael Carter, 2016-03-30 06:50:00
with human papillomavirus (HPV) types associated with a high risk of pre-cancerous
and cancerous cell changes persisted for two years in 37% of men who have sex with men
(MSM) enrolled in an international study published in Clinical Infectious Diseases. The prospective, observational study
involved 406 HIV-negative MSM recruited in Brazil, Mexico and the United
States. Among men with prevalent high-risk HPV infection, 37% retained the
infection for at least 24 months and HPV-16 infection for at least 24 months in
30% of those with this infection at baseline.
one-third of MSM exhibited persistence of prevalence high-risk types for >
24 months indicating that prevalent high-risk anal HPV infection may be a
clinically important event,” comment the investigators. “These results may help
inform future anal cancer screening that uses HPV-DNA testing.”
Incidence of anal
cancer is especially high among MSM. Vaccines are available that provide excellent
protection against infection with the HPV types especially associated with
pre-cancerous and cancerous anal cell changes. However, access to such vaccination
is limited in most healthcare settings. Information is therefore needed to
inform programmes screening for anal infection with high-risk HPV types and/or
suspicious anal cell changes.
the HPV Infection in Men (HIM) Study therefore designed a sub-study restricted
to MSM. At baseline and at intervals every six months, participants had anal
swabs which were tested for HPV infection and 13 high-risk genotypes. Only
HIV-negative men were eligible for inclusion in the study.
A total of 406
were recruited and 82% were retained over the five study visits. Most of the
men (n = 336) reported sex with men and women (MSWM) and 70 reported sex with
men only (MSOM). The median period of follow-up was two years.
There was no
significant difference in the persistence of HPV infection between MSWM and
MSOM (8.8 vs. 6.0 months, respectively). The two groups were therefore combined
in subsequent analysis.
duration of prevalent infection differed according to genotype, ranging between
14 and 27 months. Incident infections, however, were of much shorter duration. For
example the median duration of HPV-16 infection was seven months.
Of the 106 men
with high-risk infection at baseline, 37% retained this infection for at least
24 months, with 30% of men with prevalent HPV-16 infection at baseline retained
the infection for a similar period.
An analysis that
controlled for potential confounders showed that men reporting 20 or more
lifetime anal sex partners, and also those with one or more anal sex partner in
the previous three months, were over twice as likely to have persistent
high-risk infection than men with fewer partners (PR = 2.06; 95% CI,
However, men with
the highest number of lifetime female partners were 71% less likely to have
persistent infections compared to men reporting between zero and two lifetime
“These data not
only support development of anal pre-cancer screening policy, but also
appropriate counselling for MSM who have prevalent vs. incident infection at
the anal canal,” conclude the authors. “These results may also inform debates
in countries considering vaccination for males by informing anal HPV natural