Thursday, September 1, 2011

Protect the Girls -- Vaccinate the Boys!

 Mommy, why are we looking at hats for Siamese twins?

That's a photo of my then-5-year-old son J.J., shrinking in terror when I dragged him into Victoria's Secret.  Poor guy -- there's surely nothing more mortifying than bra shopping with your mom (unless it's bra shopping with your grandma). I do realize that one day, hopefully far in the future, my innocent little boy will have a very different reaction to all those scantily clad plastic torsos.  And when he reaches that age, it will be my husband's and my solemn responsibility to guide and protect him against STDs.  So naturally we'll be enrolling him in an abstinence-only sex ed program.*

Kidding, folks!  Remember, I'm Evidence-Based Mommy, not Delusional Mommy.

Last week, I reviewed the data on the HPV vaccine for girls.  In addition to cervical cancer and genital warts, HPV causes the vast majority of penile and anal cancers, although these are much rarer.  Gardasil has been FDA-approved for use in males ages 9 through 26.  So what is the evidence that it works in this population?  And now that J.J. is on the cusp of turning 9, should I be asking his pediatrician for this series of expensive shots?

As with the HPV vaccine trials in women, there are no large studies in preteens, but again, the idea behind immunizing children is to protect them before they are potentially exposed to the virus in their teens or young adulthood.  The largest trial randomized over 4000 males ages 16 to 26 to the 4-strain HPV vaccine vs. placebo.  ("Efficacy of quadrivalent HPV vaccine against HPV infection and disease in males.")  The marketing geniuses at Merck couldn't come up with a snappy acronym this time, but I liked my Scrabble-savvy friend's suggestion of SPAWN, for Stop Penectomies** and Anal Warts Now.  Six hundred of the participants reported having sex with men, a major risk factor for HPV infection.

As in the female trials, the vaccine was quite effective in patients who were uninfected at baseline, with an 84% reduction in genital lesions (mostly warts) in those who received all three shots.  The benefit in the population as a whole was significantly less, but still a decent 60% reduction.  Three precancerous penile lesions occurred in the placebo group and none in the vaccine group, but SPAWN wasn't large enough, or of sufficient duration, to detect a difference in these rare neoplasms.

Despite the clear benefit in reducing genital warts, the most frequent and more politically palatable argument for immunizing boys is to protect girls against cervical cancer.***  So should the HPV vaccine be mandatory in boys?  As much as I feel that males should shoulder some of the moral responsibility for their partners' health, in this case, I have to say no.  One of the reasons I've come to this conclusion is that cost-effectiveness analyses have shown that immunizing boys in addition to girls is extremely expensive, compared to immunizing only girls.  The excess cost ranges between $100,000 to a million dollars per year of life gained.****

Having said that, I do plan to sacrifice my eldest son on the altar of public health when his time comes.  Unfortunately for my human pincushion kids, I'm an allopathic doctor who is unabashedly pro-immunization.  Some day they'll thank me for it.

*Evidence has shown that abstinence-only programs are useless in delaying sex.  This is not to be confused with the seemingly oxymoronic abstinence-only parenting.  Telling your child, "Like hell you'll be crashing at your boyfriend's tonight!" has been shown to delay sex.
**A penectomy is an amputation of the penis, standard treatment for penile cancer.  If men were made aware of this, we would have no problem achieving 100% vaccination rates.
***For my gay readers, I apologize for this obviously hetero viewpoint.  There is a much more compelling argument to vaccinate gay males, as the incidence of anal cancer is similar to that of cervical cancer before the era of Pap smears.  The problem with vaccinating only gay males is that by the time a teenager or young adult is comfortable enough to come out of the closet, he may already be infected with HPV.
****Technically speaking, "quality-adjusted life-years" gained.  Since the most frequent manifestation of HPV infection are genital warts, and since warts don't kill you, researchers ask participants to estimate how many years of life they would be willing to give up not to have warts. One study found that having warts was as bad as losing anywhere from 1.6 to 8.3 days of life. ("Cost of treatment and QALYs lost due to genital warts.")  Hard to believe, but I guess I could see how it could get to be over a week if the warts made their cameo on, say, prom night.

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