By Daniel Peixoto IrbyUCB-UCSF Joint Medical Program, MS Candidate 2013, MD Candidate 2015
Back in 2006 when the FDA approved the HPV vaccine for girls, I remember wondering, “Why not vaccinate boys, too?” Although the FDA did subsequently approve the vaccine for use in males, it was not something that I heard much about. Which is why my eyebrows went up when I read that Australia has not only been having excellent uptake among girls and women for their HPV vaccination program, but has also, beginning February of this year, rolled out a national vaccination program for boys aged 14-15 (See the details from the Australian Cancer Council here).
The quadrivalent vaccine (Guardasil, Merck) protects against four strains of HPV. Strains 16 and 18 cause 70 percent of cervical cancers in women, and strains 6 and 11 cause 90 percent of genital warts, overall. There is also a bivalent vaccine (Cervarix, GSK) that protects mainly against HPVs 16 and 18.
Outright cervical cancer is not something we hear too much about in the US, in large part because the Pap smear is effective at catching precancerous changes that may precede cervical cancer. But in regions of the world where screening is less readily available, cervical cancer is more common: between 3 and 7 times more common (relative to the US) in Sub-Saharan Africa, South America, and Southeast Asia, according to the WHO. Cervical cancer is perhaps the
most preventable cancer -- and preventing cancer is something we should be all about.
Cancer in Men
Did you know that men can get HPV-related cancer, as well? It’s true. About 72 percent of anal cancers are caused by-- you guessed it-- HPV strains 16 and 18, the same culprits behind the majority of instances of cervical cancer. In fact, the whole sequence-- infection with HPV, precancerous changes, possible cancer about 25 years down the road-- is believed to be analogous between cervical and anal cancer. However, anal cancer has been much less studied and the healthcare system is generally less comfortable with and certainly less well-trained in obtaining anal cytology samples (“an anal Pap”).
Nevertheless, there are at least two excellent reasons for vaccinating boys and young men. First, HPV vaccines can decrease infection with those nasty HPV types highly associated with precancerous changes and outright cancer. Second, boys and men who are immunized are less likely to spread these undesireables to their female sexual partners (all takes is one time, folks).
Further, for gay and bisexual men, anal cancer in the pre-HIV epidemic period was estimated to occur at about 37 per 100,000, a rate similar to the rate of cervical cancer among women prior to widespread adoption of Pap smears. And for HIV-positive members of these groups, the risk of developing anal cancer doubles. (UpToDate: Classification and epidemiology of anal cancer).
HPV Vaccines Considered Safe for Use in Individuals with HIV
The HPV vaccines are not
live vaccines and are considered safe for use in individuals who are HIV-positive or otherwise immunocompromised. Specifically, the quadrivalent vaccine has been studied and found to be both safe and immunogenic in HIV-positive populations. This vaccine is recommended by the Advisory Committee on Immunization Practices (ACIP) for any
HIV-positive individual through the age of 26.
Which brings us back to Australia, and how it is not
like the US. While less than one-third of American girls have received an HPV vaccine, nearly 75 percent of Australian girls have over the now six-year-old campaign Down Under. This was recently found to have translated into drop-offs in genital wart cases of 59 and 39 percent, respectively, among girls and boys, and a sharp drop-off in cervical abnormalities among teenage girls. Good news for the rational Australian plan to address the estimated two-thirds of cervical cancer cases worldwide that are believed to be preventable. Why not, while we contemplate redoubling our efforts here in the US to vaccinate girls and women, make a similar push for the health of men and boys, be they straight, gay, bisexual, queer, trans, or anything else?