In the news ... 2009

HPV vaccine may be effective in boys and men

by Alan McCord, January 5, 2009

From data presented at a recent European conference on genital health in Nice, France, it appears that the HPV vaccine Gardasil prevented external genital lesions in men 16 to 26 years of age. The vaccine has not yet been approved for boys and men in the US. This study sought to see if the vaccine was also effective at preventing HPV disease in boys and men.

In the US, Gardasil is currently only approved for preventing four types of HPV in girls and women aged 9 to 26 years. Two of those types, 16 and 18, can lead to cervical, vulvar and vaginal cancers. The other two, HPV types 6 and 11, cause genital warts. Infection with HPV in men can lead to genital warts and penile and anal cancers. Nearly 25,000 cases of cervical, anal and oral cancers related to HPV infection occur in the US each year.

This phase 3 study followed 4,065 men (~3,400 heterosexual and ~600 men who have sex with men) over an average of 29 months. It divided them into two groups: one that took the vaccine at day one and then at two and six months while the other group took placebo. All were negative for the four HPV types before the start of the study with no signs of genital lesions, no history of genital warts, and five or fewer sexual partners.

The results showed that the vaccine prevented up to 90% of the external genital lesions from the four types of HPV in this cohort of men (only 3 cases in those on the vaccine vs. 31 cases on placebo). The three cases were genital warts, with no cases of genital intraepithelial neoplasia (changes in surface skin cells) or cancer in the vaccine group, though the length of this study is likely too short to adequately assess the prevention of possible neoplasia or cancer over time.

The most common adverse reaction was headache. Others included fever, nausea and dizziness as well as injection site reactions such as pain, redness, bruising, itching, tenderness and swelling. Those taking the vaccine reported slightly more injection site reactions than those on placebo.

The intent of using HPV vaccines in men is to reduce the rate of anal and penile cancers as well as to lower the infection rate of these HPV types in the general population. This may then result in fewer cases of genital warts and cancers overall. However, several distinctions can still be made about this study.

The length of study was at most 36 months for some individuals. This is a far too short amount of time to adequately assess the vaccine’s durability for the long-term, such as a decade or more. Therefore, the vaccine has not been proven to prevent cancers at this time, only the types of HPV that can lead to these cancers. Only ongoing study will better describe its effectiveness over time and other issues such as the possible need for periodic boosters.
The study also only included men with few lifetime sexual partners. So, how effective the vaccine is in men who have more than five partners is unknown.

Other questions also remain. Will getting an HPV vaccine cause men and women to refrain from getting regular Pap screening over time? How does this vaccine respond when given with other vaccines? What factors impact the vaccine’s effectiveness, such as smoking or even a weakened immune system?

These results are still important news for women and men living with HIV, who are at higher risk for HPV disease and HPV-related cancers. Indeed, nearly 1 in 1,000 HIV-positive men get diagnosed with anal cancer each year. Therefore, using medical products like a vaccine to reduce the rate of HPV infection and disease is welcomed news. More research continues to be needed for finding ways to reduce the growing rate of genital cancers in people living with HIV.