CATIE News - Vaccines for HPV-results in men
18 May 2010 - There are more than 150 strains (also called genotypes or types) of HPV (human papillomavirus). These viruses are easily
transmitted during penetrative or non-penetrative sex. HPV can infect the mouth and throat as well as the ano-genital region, both inside and outside of these delicate tissues.
Some genotypes of HPV, most commonly genotypes 6 and 11, can cause ano-genital warts. Other genotypes, most commonly genotypes 16 and 18,
can cause precancerous lesions and cancers most commonly affecting the cervix and vulva in women and the anus in both men and women, and, in rare cases, cancer of the penis in men.
A large Quebec study
While warts may seem like mere annoyances to some readers, researchers in Quebec have found that a diagnosis of ano-genital warts is accompanied
by a sharp increase for the risk of something more serious-anal cancer.
Quebec researchers reviewed anonymous health information in the Quebec Tumour Registry and cross-checked it with Régie d'assurance
maladie du Québec databank. Then they used this information to estimate the risk of anal cancer in people who had been diagnosed and treated for ano-genital warts. The
research team found that between 1990 and 1999, 20,825 patients were treated for anal warts, on average at least three times.
In the Montreal region, 66% of patients with ano-genital warts were male, and males were also treated more frequently for these warts than women.
Eighty percent of patients were between the ages of 15 and 44 years.
In the study period, a total of 15 cases of anal cancer occurred in people who had been treated for ano-genital warts. Fourteen of these cases
were in the greater Montreal area. The study found that the relative risk for anal cancer among these people who had ano- genital warts increased more than 200-fold. Similar
research in the U.K. has also found a disproportionate increased risk for anal warts among men who have sex with men (MSM) compared to men who have sex with women.
In summary, on average, about 2,000 people each year in Quebec are diagnosed with ano-genital warts and could be considered at high risk
for anal cancer. Routine screening for anal cancer is not available, unlike that for cervical cancer.
In another study also by Quebec researchers, most anal cancers contained HPV and most of these contained HPV 16.
Vaccines
Two vaccines that have demonstrated their ability to reduce the risk of developing HPV-related cancer in HIV-negative women are approved in
many high-income countries under the following names:
- Cervarix - offers protection against HPV 16 and 18
- Gardasil - offers protection against HPV 6, 11, 16 and 18
Because of the absence of data, researchers were not sure that these vaccines could work in gay and bisexual men. However, results from a
subset of MSM from a large trial of Gardasil in young men recently became available. Below is a summary of that data.
A vaccine tested in men
The trial, called the Quadrivalent Study, enrolled 4,065 men, aged between 16 and 26 years, of whom 602 disclosed that they had sex with men.
These men also disclosed that they had five or fewer male sexual partners in their lifetime. Once the men were in the study, researchers analysed their anal swabs and blood
samples and found the following infections:
- anal Chlamydia - 9%
- syphilis - 3%
- HIV - 2%
- gonorrhea - 1%
The men had no evidence of genital warts or lesions and tested negative for HPV antibodies and its genetic material.
The men received three injections of either vaccine or placebo at months zero, two and six of the study.
After an average of 30 months of monitoring, researchers found the following among gay and bisexual men:
- vaccine recipients - 5 of 194 men developed precancerous anal lesions
- placebo recipients - 24 of 208 men developed precancerous anal lesions
There were no cases of anal or other HPV-related cancers in this study and no serious vaccine-related side effects occurred.
The findings from this study suggest that Gardasil reduces the risk of developing pre-cancerous anal lesions in young men about five-fold-a
significant benefit. Bear in mind that these young men had, at most, five sexual partners in their lifetime prior to vaccination.
These findings will likely be submitted to regulatory authorities in high-income countries over the coming year and should encourage young
gay and bisexual men to get vaccinated against HPV.
Another potential reason for HPV vaccination
Many sexually transmitted infections, such as syphilis and herpes, can increase the risk of HIV transmission by causing sores, lesions or
inflammation. HPV may be no different. This is because infection with warts stimulates the immune system, causing inflammation and drawing large numbers of activated cells
of the immune system near the surface of the skin. Activated immune cells are susceptible to HIV infection. Therefore, vaccination against HPV may have a role to play in
reducing the risk of HIV infection.
What about co-infection?
Because both HPV and HIV are sexually transmitted, co-infection with both viruses is common. Researchers are uncertain about the impact
of vaccinating HIV-positive people with HPV vaccines. Specifically, will the immune systems of such people be able to respond to the vaccines and would this response
help prevent HPV-related complications? Preliminary results suggest that immunization with Gardasil is safe and stimulates production of HPV antibodies to levels
almost as high as in HIV-negative men.
Clinical trials in Canada and the U.S. are underway to assess Gardasil's safety and ability to stimulate HPV antibodies in
HIV-positive women. For information about the Canadian trial visit this site:
www.hivnet.ubc.ca/clinical-studies/canadian-hiv-trials-database/ctn-236/
So far, no large trials are underway to assess the ability of Gardasil or Cervarix to reduce the risk of HPV-related cancers in HIV-positive people.
Acknowledgement
We thank Marc Steben, MD, Institut national de santé publique du Québec, Montreal, for helpful review, discussion and research assistance.
-Sean R. Hosein
REFERENCES:
• Steben M, Louchini R and Duarte-Franco E. High risk of anal cancer in individuals treated for anal condyloma in a population-based transversal
study in Quebec (Canada), 1990-1999. In: Program and abstracts of the 18th International Society for Sexually Transmitted Disease Research, June 28- July 1, 2009. London, UK.
• Palefsky J, for the male quadrivalent HPV vaccine efficacy trial team. Efficacy of Gardasil in men aged 16-26 years naïve to vaccine HPV
types at baseline: the latest data. In: Program and abstracts of the European Research Organization on Genital Infection and Neoplasia , 17-20 February 2010, Monte Carlo, Monaco.
Abstract TC 4-2.
• Palefsky J, for the male quadrivalent HPV vaccine efficacy trial team. Quadrivalent HPV vaccine efficacy against anal intraepithelial neoplasia
in men having sex with men. In: Program and abstracts of the European Research Organization on Genital Infection and Neoplasia , 17-20 February 2010, Monte Carlo, Monaco.
Abstract SS 19-2.
• Wilkin T, Lee J, Goldstone S, et al. Safety and immunogenicity of the quadrivalent HPV vaccine in HIV-infected men: primary results of the AIDS
Malignancy Consortium Trial 052. In: Program and abstracts of the 17th Conference on Retroviruses and Opportunistic Infections , 16-19 February 2010, San Francisco, U.S. Abstract 1015.
• Smith JS, Moses S, Hudgens MG, et al. Increased risk of HIV acquisition among Kenyan men with human papillomavirus infection. Journal of
Infectious Diseases . 2010 Jun 1;201(11):1677-85.
From Canadian AIDS Treatment Information Exchange (CATIE). For more information visit CATIE's Information Network at http://www.catie.ca
Source: CATIE: CANADIAN AIDS TREATMENT INFORMATION EXCHANGE
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