Author: Kate Johnson
Date: May 18, 2017
Source: http://www.medscape.com/viewarticle/880184#vp_1

Human papillomavirus (HPV) vaccination is associated with an 88% reduction in rates of oral HPV infection according to one of the first studies to investigate this association.

The findings, reported in a premeeting presscast for the American Society of Clinical Oncology (ASCO) 2017 Annual Meeting, suggest that HPV vaccination may play an important role in the prevention of oropharyngeal cancer.

“Our data indicate that HPV vaccines have tremendous potential to prevent oral infections,” said senior study author Maura L. Gillison, MD, PhD, who conducted the research at Ohio State University and is now a professor of medicine at the University of Texas MD Anderson Cancer Center in Houston.

But she emphasized that although more than 90% of oropharangeal cancers are caused by HPV-16 ― one of the types for which HPV vaccines are currently available ― the vaccine is only indicated for the prevention of cervical and anogenital infections and associated cancers.

“There haven’t been any clinical trials evaluating whether the currently approved HPV vaccines can prevent oral infections that lead to cancer, so that is not currently an indication,” she explained.

In the absence of randomized trials, Dr Gillison and colleagues carried out a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) survey collected from 2627 young adults aged 18 to 33 years during the period 2011-2014.

This study was conducted by the National Center for Health Statistics and was designed to assess the health and wellness of the US population. Since 2009, Dr Gillison and colleagues have collaborated with NHANES to study oral HPV infections and have analyzed oral rinse samples collected by mobile health facilities.

Comparing individuals who had received the HPV vaccine (29.2% of women and 6.9% of men; P < .001) to those who had not, the analysis found the prevalence of oral HPV infections covered by the vaccine (HPV-16, -18, -6, and -11) was significantly lower in the vaccinated group (0.11% vs 1.61%; P = .008).

The most significant reduction was seen in men. None of those who had been vaccinated had an HPV infection of the types for which vaccinations were available, compared to 2.1% of unvaccinated men (P = .007).

“We were particularly interested in infections among men because the burden of HPV caused by head and neck cancer is largely borne by men, and the rates are rising most dramatically among men,” she said. The prevalence of HPV-positive oropharyngeal cancer is increasing faster than that of any other cancer among young, white, American men, she added.

“Using thse data, we estimated in an unvaccinated population about a million young adults would have oral HPV infection by one of these types, and if vaccines were universally accepted, we could have prevented perhaps over 900,000 of those,” she said.

HPV vaccines are recommended by a number of organizations, including the Centers for Disease Control and Prevention, the National Comprehensive Cancer Network, and ASCO, as well as a coalition of the top US cancer centers.

They were approved by the US Food and Drug Administration in 2006 for female patients aged 9 to 26 years; in 2011, they were approved for male patients aged 9 to 21 years (for men who have sex with men, they were approved to the age of 26 years).

However, in the 2011-2014 survey, only 18.3% of this population reported being vaccinated (6.9% of men and 29.2% of women).

Given this low uptake, the researchers estimated that “only 17% of potentially preventable infections have been prevented, 25% in women and a modest 7% in men,” said Dr Gillison.

Despite this, there is “considerable optimism,” she added.

“Recent data indicate that in individuals under the age of 18, 60% of girls have received more than one vaccine and 40% of boys – so vaccine uptake is higher now,” she added.

Dr Gillison warned against concluding on the basis of this study that there is a causal relationship between vaccination and prevention, because this was not a prospective trial. “Nevertheless, we can conclude that HPV vaccination may have additional benefits beyond prevention of anogenital cancers,” she said.

“The HPV vaccine has the potential to be one of the most significant cancer prevention tools ever developed, and it’s already reducing the world’s burden of cervical cancers,” said ASCO President-elect Bruce E. Johnson, MD, from the Dana-Farber Cancer Institute​ in Boston, Massachusetts.

“The hope is that vaccination will also curb rising rates of HPV-related oral and genital cancers, which are hard to treat. This study confirms that the HPV vaccine can prevent oral HPV infections, but we know it only works if it’s used.”

Approached for comment, Carole Fakhry, MD, from Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, said the results are promising, but further work is necessary.

“There have been no prospective studies to date that evaluate the impact of the vaccine on oral HPV infection,” Dr Fakhry told Medscape Medical News. “It is reassuring to see that the vaccine helps reduce oral HPV infections ― that was previously largely unknown ― [but] we can’t extrapolate from anogenital HPV [data].”

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