Recent data linking human papillomavirus with oropharyngeal cancers, which typically occur in men, suggest a need for stepped-up efforts to gain approval for use of the HPV vaccine in young men and adolescent boys, according to Dr. Erich Sturgis and Dr. Paul M. Cinciripini, of the University of Texas M.D. Anderson Cancer Center, Houston.
Although the incidence of most types of squamous cell carcinomas of the head and neck have declined over the past 20 years, in tandem with declines in the prevalence of smoking, the incidence of oropharyngeal cancers has remained stagnanta trend that may be attributable to the growing incidence of oncogenic HPV-associated cancers, the authors stated in the report (Cancer 2007 Oct. [doi:10.1002/cncr.22963]).
"We encourage the rapid study of the efficacy and safety of [HPV-16/18] vaccines in males and, if successful, the recommendation of vaccination in young adult and adolescent males," they wrote.
They praised efforts to promote the recently approved HPV-16/18 vaccination of young women and adolescent girls to reduce the incidence of cervical cancer and dysplasia, but warned that limiting vaccination programs to women and girls would delay potential benefits of preventing the HPV-16/18 oropharyngeal cancers in males.
Dr. Cinciripini has acted as a consultant for GlaxoSmithKline, the manufacturer of Cervarix, a vaccine against HPV 16/18.
Their recommendation is based on a number of factors. Data have confirmed an increase in the incidence of oral tongue cancer in young adults and of oropharyngeal cancersparticularly tonsil and base of tongue cancerin those younger than 45 years.
In addition, the literature consistently shows a link between oncogenic HPV and oropharyngeal cancers, with HPV DNA being identified in about half of all oropharyngeal cancers and in a particularly high proportion of oropharyngeal cancers in nonsmokers. More than 90% of HPV-positive oropharyngeal cancers are a result of HPV-16.
"The association is also quite strong with a significant risk of oropharyngeal cancer reported in epidemiologic case-control studies by numerous independent investigators and after adjustment for smoking and alcohol exposures," the authors wrote.
The similarities between HPV-related oropharyngeal cancer and cervical carcinogenesis, and the "biologic plausibility of the HPV carcinogenesis model all support HPV causality of a proportion of oropharyngeal cancers," they noted.
The mode of transmission of HPV in patients with HPV-related oropharyngeal cancer is not clear, but some reports suggest that the sexual history of oncogenic HPV-positive oropharyngeal cancer patients mirrors that of women with cervical cancer, and it is likely that risk factors such as multiple sexual partners and oral-genital sex play a role, they stated.
Lending further credence to this possibility is the reported increase in the frequency of oral sex in adolescents, which could be a contributing factor in the increase in HPV-associated oropharyngeal cancers in young adults.
Data from the Swedish Cancer Registry show that the prevalence of HPV-16 in oropharyngeal cancer specimens increased from 23% in the 1970s to 28% in the 1980s, 57% in the 1990s, and 68% in the 2000s, despite dramatic declines in smoking prevalence.