Human 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.
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