A study published in the October 3, 2011, issue of the Journal of Clinical Oncology reveals a startling rise in the rate of throat cancers related to human papillomavirus (HPV). The study looked at specimens from 271 throat cancers (specifically oropharyngeal squamous cell carcinomas, or OPSCC) collected over 20 years. The researchers found that HPV prevalence in the cancers increased from 16.3% during 1984 to 1989 to 71.7% during 2000 to 2004. They note that “The overall rise in OPSCC incidence during 1984 to 2004 is largely explained by the increasing incidence of HPV-positive cancers, whereas incidence of HPV-negative cancers declined.”
The decline in non-HPV related oropharyngeal cancers, which are usually related to tobacco or alcohol use, is likely a result of lower tobacco exposure. The HPV-related cancers, as opposed to the non-HPV-related cancers, were more likely to occur in younger, male, and white individuals. The authors speculate that the increased incidence “perhaps arises from increased oral sex and oral HPV exposure over calendar time.”
HPV is primarily known for its role in causing cervical cancer. Two strains of the virus – strains 16 and 18 – are estimated to be responsible for 70% of cervical cancer cases, leading to about 500,000 new cases and 270,000 deaths worldwide each year. The licensed HPV vaccines have been shown to be effective in preventing cervical infection with strains 16 and 18, both cancer-causing strains. HPV vaccination is currently recommended for all U.S. girls at age 11-12. The Advisory Committee for Immunization Practices has since October 2009 supported “permissive” but not routine use of the vaccine for boys.
We spoke with Paul A. Offit, MD, chief of Infectious Diseases at The Children’s Hospital of Philadelphia, about the new study and its implications for HPV vaccination for boys. When asked whether we have evidence that HPV vaccination prevents throat cancers in males, Offit said, “What we do have is evidence that HPV vaccination can prevent infection. And since we know that a cell cannot become cancerous [with HPV-related cancer] unless it was infected with HPV, then the vaccine will protect against oropharyngeal cancers in men.”
Moreoever, Offit noted that we do not have direct evidence that HPV vaccination prevents cervical cancer in girls; what we have is compelling evidence that the vaccine prevents the cervical intraepithelial neoplasias that are requisites for cervical cancers. “So, for boys, we have the same thing: a cell can’t be transformed unless it is infected with HPV. And we have data that the vaccine prevents infections.”
Offit thinks that the recommendation for HPV vaccination for boys will come soon, possibly at the end of this month when the Advisory Committee for Immunization Practices meets. The topic is on the committee’s agenda for Tuesday, October 25.
As Offit says, “The recommendation will help prevent spread of the virus from men to women and will protect men from HPV-related cancers.”
Chaturvedi AK, Engels EA, Pfeiffer RM, et al. Human papillomavirus and rising oropharyngeal cancer incidence in the United States. J Clin Onc. 10.1200/JCO.2011.36.4596 http://jco.ascopubs.org/content/early/2011/10/03/JCO.2011.36.4596
AAFP News Now. ACIP supports ‘permissive use,’but not routine use, of Gardasil in males. 10/27/2009. http://www.aafp.org/online/en/home/publications/news/news-now/clinical-care-research/20091027acip-hpv-vacc.html