Monday, February 22, 2016

Big Drop in Cancer-Causing HPV Following Vaccination, But Rates of Vaccination in US Lag

by Hank Dart

Thirteen years ago, in an earlier incarnation of Cancer News in Context, we wrote our very first post about the potential of the HPV vaccine following the release of a promising study in the New England Journal of Medicine. That post - "A Shot in the Arm for Cervical Cancer Prevention" -  concluded:
"While much work remains before there is any sort of widespread cervical cancer vaccination program in the U.S. or abroad, the results of this initial study spawn a realistic hope that over the next decade or so great strides will be made in preventing cervical cancer the world over."
Well here we are, that decade or so on from the original post, and the latest news on the HPV vaccine - as reported in today's New York Times - is quite positive, but with a number of important caveats.

HPV (human papillomavirus) is a common sexually transmitted infection, and certain types of HPV are a primary cause of cervical cancer. It's estimated that nearly all adults - men and women - are infected with HPV at some point in their lives. While the body naturally clears most of these infections, some can persist, increasing the risk of cervical (and a number of other) cancers.

New national data, as reported in the Times and published in the journal Pediatrics today, show that in the six years after 2006, when the HPV vaccine became available for girls, rates of infection with four main cancer-causing types of HPV(6, 11, 16, and 18) have dropped dramatically - as much as 64 percent in younger females (age 14 - 19), the age group that had been the most widely vaccinated.

Though only time, and data, will tell for sure, such findings seem likely to translate to significantly lower future rates of cervical cancer in today's groups of vaccinated girls and young women.

Alongside such positive news, however, is the fact that the HPV vaccine remains frustratingly underused in the United States.  As we wrote about in 2014, vaccination rates for the HPV vaccine are much below those of other childhood vaccines.  The most recent numbers show that only 38 percent of girls in the United States receive the complete 3-shot series of the HPV vaccine.  Boys' numbers are even lower - at 14 percent.  And low as these are, they are modest improvements from pervious years.

In comparison, in Australia, where the vaccine is offered for free at schools as part of its national immunization program, rates of full 3-dose HPV vaccination in girls is over 70 percent by age 15.

No such integration into systems has happened in the United States, and HPV vaccination remains in many ways on the fringe.  Though it has huge potential to prevent cervical cancer - as well as to lower the risk of anal, throat, and penis cancers, as well as genital warts - many physicians aren't proactive in suggesting vaccination, many parents don't know to request it,  and both groups may not be perfectly clear on its safety, effectiveness, and ultimate purpose of preventing cancer.

Clearly, there has been a lot of progress since our post in 2003 but perhaps not surprisingly it has been at a pace slower than hoped.  To be sure, there have been some "great strides" in further developing the vaccine, in documenting its safety and effectiveness, and - in certain countries - developing model vaccination programs.

But there is still a great deal of work to do before we tap the HPV vaccine's full potential in the United States - as well as worldwide.  This latest study shows the likely benefits of developing a better-integrated HPV vaccination program.  Let's use it to spur on coordinated efforts toward that important end.

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