A large number of
infections with anal cancer-associated strains of human papillomavirus (HPV)
among older gay men could be prevented with the use of HPV vaccines, Australian
research presented to the recent 7th International AIDS Society Conference on HIV Pathogenesis, Treatment
and Prevention in Kuala
were especially likely to have anal infection with a high-risk strain of HPV at
baseline and to have incident infections over three years of follow-up.
the Study of the Prevention of Anal Cancer (SPANC) in Sydney undertook the
research because of the high prevalence of anal HPV infection among gay men,
especially those infected with HIV.
with a high-risk strain of HPV can lead to anal cell changes that can lead to
cancer. The rate of anal cancer is especially high among HIV-positive gay men
at 100 cases per 100,000.
HPV vaccine (qHPV, Gardasil) provides a high degree of protection against infection with
HPV types 6, 11, 16 and 18; types 6 and 11 are associated with genital warts and types 16 and 18 with anal and genital cancers. In Australia, the vaccine has been recommended for school-age girls since
2007 and for boys since 2013. The vaccine is approved for women up to the age
of 45 and recommended only for men aged 26 and under, due to a lack of data in older male populations.
A nonavalent HPV vaccine (nHPV) is currently being developed by Merck & Co. This is designed to provide protection against a broader
spectrum of HPV genotypes including HPV 6, 11, 16, 18, 31, 33, 45, 52 and 58.
wanted to establish the potential impact of vaccination with qHPV or nHPV on
the incidence of anal HPV infection among older gay men. They especially wanted
to see if HIV infection and age were risk factors for infection with high-risk
strains of HPV.
A total of 342 gay
men aged 35 and older were recruited to the study between 2010 and 2013. They
were screened at baseline for infection with HPV types covered by qHPV and
nHPV. Over three years of follow-up, the participants were also examined for
incident high-risk HPV infections.
The participants had a
mean age of 49 years (range: 35 to 79) and 29% were HIV positive. The vast
majority (89%) of HIV-positive men were taking antiretroviral therapy. This treatment
was achieving good control of HIV, with 84% having an undetectable viral load
and 83% a recent CD4 cell count above 350 cells/mm3.
At baseline, 51%
of men were infected with an HPV type covered by qHPV and two-thirds with a
strain preventable with nHPV. The most common HPV type was HPV16 (the most
common HPV type associated with anal cancer), which was detected in 30% of
Over the three
years of the study, there was a high incidence of cancer-associated HPV types.
A fifth of men
each year became newly infected with a strain of HPV covered by qHPV and 27% with a
type covered by nHPV.
The HPV type commonly associated with genital warts (HPV6) was the most
commonly detected type in new infections (9 per 100 person-years), followed by two high cancer-risk HPV types, HPV45 (8 per 100 person-years) and HPV16 (5 per 100 person-years).
Infection with HIV
was a risk factor for the presence of high-risk HPV types at baseline (p =
0.002) and incident infections during follow-up (p = 0.033). There were no
significant associations with age.
therefore conclude that there is a high prevalence and incidence of HPV strains
covered by both HPV vaccines among older gay men, especially among men with
HIV. They believe their findings could have implications for vaccination
strategies as “prophylactic qHPV and nHPV vaccination of older homosexual men
would prevent future HPV-associated disease”.