Thursday, May 9, 2013

Human Papillomavirus Vaccine - why the controversy?

I have been preparing for an interview about Human Papillomavirus (HPV) and the HPV vaccine.  There has been some controversy around this vaccine, mostly as it relates to some state governments mandating the vaccine through schools (1).  I admit that as an Infectious Disease doctor, I am an advocate of vaccines, but I did a little research on the topic so as not to sound like a total fool in the interview.  

The quadravalant vaccine is Gardasil, from Merck.  It covers strains 6, 11, 16 and 18.  Strains 6 and 11 account for 90% of genital warts, and 16 and 18 account for 70% of cervical cancers.  Right now, the vaccine is recommended for girls and boys ages 11-12, but can be given in ages 13-26 if they haven't been vaccinated previously.  It is a 3 shot series given over 6 months (2).  

Genital warts are associated with depression, sexual dysfunction and a disruption in long-term relationships. 

HPV is associated with a lot of types of cancer:

-       Cervical cancer: Almost all are linked to HPV.  12,000 US women per year are diagnosed, 4,000 die per year.  
-       Vulvar cancer: 50% linked to HPV
-       Vaginal cancer: 65% linked to HPV
-       Penile cancer: 35% linked to HPV
-       Anal cancer: 95% linked to HPV
-       Oropharyngeal cancer*: 60% linked to HPV (3)

Now, it is important to note that not every women who gets a high risk strain of HPV (most commonly 16 and 18) will get cervical cancer.  One expert stated that 95% of women who have HPV will never have a malignant transformation - they will not get cancer (4).  The problem is that right now, we are not able to predict which women will, and which will not, get cancer.  

When I was in medical school, part of our obstetrics rotation was to do 2 weeks on Gyn-Onc, which was short hand for "gynecologic oncology."  This was an extremely sad rotation, where I helped to care for women with gynecologic cancers.  Most of them were too young to be battling cancer.  Most them had children.  Most of them did not do well.  When you have to watch a young mom die of cervical cancer, it influences your perspective on the cancer vaccine.  

I understand the controversy: we are recommending that girls who are too young to be having sex get a vaccine to prevent a sexual disease which might lead to cancer.  The point is to vaccinate these girls and boys before they start being sexually active.  And sexually active is more than just sex.  Noncoital contact (eg., oral-genital contact and hand-genital contact) can spread HPV.  One study looked at girls prior to their first vaginal intercourse, and found that of those who were positive for HPV, 10% had never had any sexual contact and 90% had at least one episode of noncoital contacts (Shrew ML et al. High Frequency of Human Papillomavirus Detection in the Vagina Before First Vaginal Intercourse Among Females Enrolled in a Longitudinal Cohort Study. J Infect Dis 2013;207:1012-15).  

Vaccination makes sense to me.  I agree with one parent who said that the repulsion to this vaccine is probably not due to the science behind or efficacy of the vaccine.  It's probably due to parents getting a little squeamish thinking about their 11 year old daughters some day (soon?) becoming sexually active.  It's probably a little unnerving to think about that messy-haired girl with dirty fingernails in sweatpants starting to come in to her own sexuality.  Unfortunately, saying no to the vaccine is not going to put the brakes on her development.  She will grow and find love - the puppy kind, the right kind and the wrong kind - and I think that parents should be willing to protect their daughters (and sons) from a potentially deadly, and very preventable, infection.

*I saw a young patient with HPV of the larynx, and he had multiple laser surgeries to remove the growths, but they kept coming back.  He couldn't breath and eventually couldn't talk.  His HPV spread to the lungs, and he was diagnosed with terminal lung cancer.