HPV and the Rise of Head and Neck Cancers

Ben Leach
Published: Friday, Feb 03, 2012

Many head and neck cancers are caused by HPVHuman papillomavirus is perhaps best known as the main cause of cervical cancer, but if recent trends continue, by 2020 HPV will cause more cases of oropharyngeal cancer each year than cervical cancer. Changes in public perceptions of the virus, as well as in sexual habits, are necessary to slow the spread of HPV-positive head and neck cancer, and experts are calling for widespread HPV vaccination of boys as well as girls, despite the lack of clinical trial evidence to support HPV vaccination for head and neck cancers.

Human papillomavirus (HPV) is the most common sexually transmitted infection, with more than 100 different strains and approximately 6.2 million new infections reported in the United States each year, according to the Centers for Disease Control and Prevention (CDC). Although less than 1% of infections lead to cancer, HPV is responsible for thousands of new cases of cervical, vulvar, vaginal, and anal cancers each year, and is the leading cause of cervical cancer, according to the CDC.

Experts have long suspected a link between HPV and oropharyngeal cancer, and an increasing body of evidence supports this association. A study of 100 patients with newly diagnosed oropharyngeal cancer and 200 matched case controls, published in 2007 in The New England Journal of Medicine, found that the HPV 16 strain was present in 72% of cancerous tumors. [D’Souza G et al. N Engl J Med. 2007;356:1944-1956.] Prior HPV infection increased the risk of oropharyngeal cancer by a factor of 32—more than the 3-fold increase in risk for smoking and the 2.5-fold increase for drinking. Oral-genital contact was strongly associated with oropharyngeal cancer, suggesting oral sex as the main route of transmission for oral HPV infection.

The incidence of oropharyngeal cancers has been rising for nearly 40 years, and a study in a recent issue of the Journal of Clinical Oncology provided empirical evidence linking the increase to HPV infection. Researchers determined HPV status for 271 oropharyngeal cancers, from 1984 to 2004, collected by the 3 population-based cancer registries in the Surveillance, Epidemiology, and End Results (SEER) Residual Tissue Repositories Program [Chaturvedi AK et al. J Clin Oncol. 2011;29:4294-4301.]. The population-level incidence of HPV-positive oropharyngeal cancers increased by 225% (95% CI, 208%-242%) from 1988 to 2004 (from 0.8 per 100,000 to 2.6 per 100,000). At the same time, the incidence of HPV-negative cancers declined by 50% (95% CI, 47%-53%; from 2.0 per 100,000 to 1.0 per 100,000), a trend that parallels the decline in smoking—a risk factor for head and neck cancer—in the United States.

The researchers predicted that, should these incidence trends continue, by 2020 the number of HPV-positive oropharyngeal cancers will surpass cervical cancers. In addition, they expect that HPV-positive oropharyngeal cancers will constitute the majority of head and neck cancers in the United States in the next 20 years.

HPV Vaccines, Oropharyngeal Cancer, and Public Health Implications

The increasing incidence of HPV-related head and neck cancers has important public health implications. Two vaccines are currently available for the prevention of HPV infection. Gardasil [human papillomavirus quadrivalent (Types 6, 11, 16, and 18) vaccine, recombinant], manufactured by Merck, was approved by the FDA in 2006 for use in females ages 9 to 26 years for the prevention of certain diseases caused by HPV, including cervical, vulvar, vaginal, and anal cancers. Three years after the initial approval for use in girls, Gardasil was later approved for use in males ages 9 to 26 years for the prevention of anal cancer, genital warts, and associated precancerous lesions due to HPV. Cervarix [human papillomavirus bivalent (types 16 and 18) vaccine, recombinant], manufactured by GlaxoSmithKline, was approved by the FDA in 2009 for similar indications for girls and women ages 10 through 25 years.

In an editorial accompanying the Chaturvedi study in the Journal of Clinical Oncology, Mroz and colleagues note that because currently available HPV vaccines are only effective before infection has been established, it is up to primary care providers to inform parents of boys (not just girls) about the risks of HPV-associated tumors and the likely reduction in risk provided by vaccination. [Mroz EA et al. J Clin Oncol. 2011;29:4222-4223.] Such efforts, however, are impeded by several issues.

First, there is the perception among the public, as well as among some healthcare providers, that the vaccine is not appropriate for boys. This may be due in part to efforts by Merck to lobby state legislatures for mandatory vaccinations for 11- and 12-year-old girls. However, the lobbying effort was dropped in 2007 amidst a storm of controversy that mostly centered around whether mandatory vaccination was implicitly sanctioning sexual activity in this young population.

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