Shedding Light on the Importance of HPV Vaccination

Shedding Light on the Importance of HPV Vaccination
Shedding Light on the Importance of HPV Vaccination

In an interview with The Guardian, Michael Douglas revealed that his throat cancer was not a product of his past drinking and smoking, but rather caused by human papillomavirus (HPV) passed on from oral sex. HPV is the most common sexually transmitted infection with an estimated 20 million people currently infected in the U.S . Most HPV infections are asymptomatic and transient.  However, in some people, HPV can develop into genital warts, cervical cancer, and other types of cancer (eg, oropharnygeal). While oropharnygeal cancer due to HPV infection is not common, a study published in the Journal of Clinical Oncology states that there is an increase in population-level incidence of these types of cancers caused by HPV.

Two HPV vaccines have been approved by the FDA to prevent HPV-related diseases. In 2006, the FDA approved Merck's Gardasil, a quadrivalent HPV vaccine indicated in girls and women 9 through 26 years of age for the prevention of the following diseases caused by HPV types included in the vaccine:

  • Cervical, vulvar, vaginal, and anal cancer caused by HPV types 16 and 18
  • Genital warts (condyloma acuminata) caused by HPV types 6 and 11

And the following precancerous or dysplastic lesions caused by HPV types 6, 11, 16, and 18:

  • Cervical intraepithelial neoplasia (CIN) grade 2/3 and Cervical adenocarcinoma in situ (AIS)
  • Cervical intraepithelial neoplasia (CIN) grade 1
  • Vulvar intraepithelial neoplasia (VIN) grade 2 and grade 3
  • Vaginal intraepithelial neoplasia (VaIN) grade 2 and grade 3
  • Anal intraepithelial neoplasia (AIN) grades 1, 2, and 3

Four years later, Gardasil was approved for use in boys and men 9 through 26 years of age for the prevention of the following diseases caused by HPV types included in the vaccine:

  • Anal cancer caused by HPV types 16 and 18
  • Genital warts (condyloma acuminata) caused by HPV types 6 and 11

And the following precancerous or dysplastic lesions caused by HPV types 6, 11, 16, and 18:

  • Anal intraepithelial neoplasia (AIN) grades 1, 2, and 3

 

In 2009, the FDA licensed bivalent HPV vaccine Cervarix (GlaxoSmithKline) for use in females aged 10 through 25 years. Cervarix is indicated to prevent cervical cancer, cervical intraepithelial neoplasia (CIN) grade 1, grade 2 or worse and adenocarcinoma in situ (AIS), caused by HPV types 16 and 18.

The bivalent HPV vaccine prevents the two HPV types, 16 and 18, which cause 70% of cervical cancers.  The quadrivalent HPV vaccine prevents four HPV types: HPV 16 and 18, as well as HPV 6 and 11, which together cause 90% of genital warts.  Quadrivalent vaccine has also been shown to protect against cancers of the anus, vagina and vulva. Only the quadrivalent vaccine is licensed in use for males. While both vaccines are effective in preventing HPV-related diseases, a study published in the BMJ demonstrated that the bivalent vaccine may be more effective in preventing death due to cervical cancer.

Both HPV vaccines have no therapeutic effect on HPV-related disease, so they will not treat existing diseases or conditions caused by HPV. The vaccines are made from non-infectious HPV virus-like particles (VLPs) and do not contain thimerosal or mercury as a preservative.

Ideally, patients should be vaccinated before onset of sexual activity, when they may be exposed to HPV. Patients who have been infected with one or more HPV types still get protection from the vaccine types they have not acquired. 

Either HPV vaccine is routinely recommended for 11- or 12-year-old girls. Quadrivalent HPV vaccine is routinely recommended for 11- or 12-year-old boys. The vaccine series can be started beginning at age 9 years. Vaccination is also recommended for 13- through 26-year-old females and 13- through 21-year-old males who have not completed the vaccine series. Quadrivalent HPV vaccine may be given to 22- through 26-year-old males. Vaccination is routinely recommended for both men who have sex with men (MSM) and immunocompromised persons aged 22 through 26 years.

The CDC recommends that healthcare providers recommend HPV vaccination the same way they recommend other adolescent vaccines. Parents may be hesitant to vaccinate their children because they believe that vaccinating may be perceived by the child as permission to have sex.  Clinicians should be ready to discuss the importance of vaccination with parents and how it may help protect the child from HPV-related cancers in the future.  Data from the 2011 National Immunization Survey showed that among females and males who initiated the HPV series, 70.7% and 28.1% received 3 doses, respectively. These numbers indicate that girls still seem to be the primary focus for vaccination.

While neither of these vaccines has been studied in the prevention of oropharyngeal cancers, it is still important for patients to be vaccinated to prevent other HPV-related diseases. Healthcare providers should also counsel patients on appropriate barrier methods that may be used during oral sex. Michael Douglas may have brought HPV and oropharyngeal cancer into the news, but it is the clinician's responsibility to answer the relevant questions surrounding the disease.

For more information visit www.cdc.gov/std/hpv/stdfact-hpv-vaccine-hcp.htm
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