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The human papillomavirus (HPV) vaccine may reduce the rate of oral HPV infections in young adults by as much as 88%, reports the University of Texas MD Anderson Cancer Center. But the vaccine’s low rate of usage in the United States, especially among males, has left it with little impact on the actual rate of oral HPV infections.
The Centers for Disease Control and Prevention have linked HPV with about 70% of oropharyngeal cancers, and that rate is rising. However, no clinical trials have prospectively evaluated whether existing HPV vaccines will prevent oral infections that lead to the disease. So, they have not been approved for the prevention of head and neck cancers, only the prevention of cervical, vulvar, vaginal, and anal cancers in women and anal cancers in men.
“We don’t know if there’s a potential solution to these rising rates already existing on the shelves,” said Maura L. Gillison, MD, PhD, professor of thoracic/head and neck medical oncology at the center. She had conducted the study while she was at the Ohio State University Comprehensive Cancer Center. “In the absence of that gold standard clinical trial, we looked at data from a study that we’ve been conducting in my lab to address the question as to whether or not existing HPV could be altering oral HPV infections in the US population.”
The researchers analyzed data from 2011 to 2014 from the National Health and Nutrition Examination Study. Starting in 2011, participants began to self-report if they had received one or more HPV vaccines. The researchers analyzed responses from 2,627 young adults aged 18 to 33 years and compared the prevalence of an oral HPV infection in those who received one or more doses of the vaccine to those who did not.
At that time, about 18.3% of young adults in the United States reported receiving one or more vaccine dose by the age of 26 years. Vaccination was more common in women than men, at 29.2% to 6.9%, respectively. Also, the researchers evaluated the prevalence of HPV type 16, 8, 6, and 11, which are the 4 types included in HPV vaccines prior to 2016.
The prevalence of vaccine-type infections was far less common in individuals who had been vaccinated versus those who had not been vaccinated. Comparing the groups, the infection rates in the vaccinated group was about 88% lower than those individuals who had not been vaccinated. And since HPV-positive head and neck cancers disproportionately affect men, the researchers want to know if the vaccine is associated with a reduced prevalence in men.
“When we compared the prevalence in vaccinated men to non-vaccinated men, we didn’t detect any infections in vaccinated men. The data suggests that the vaccine may be reducing the prevalence of those infections by as high as 100%,” said Gillison.
Furthermore, the researchers looked at the potential effect of HPV vaccination on the burden of infections in this age group. Given that this was a statistically representative sample, the researchers could estimate how many individuals in this age group would have an oral HPV infection in a vaccinated versus a non-vaccinated population.
“We also wanted to determine, accounting for the low rates of vaccination, what proportion of infections could have been prevented,” said Gillison. “We found that just under one million people would have HPV infections in this age group. But, unfortunately, because of low uptake of the vaccine, the burden of infection had only been reduced by 17% overall, and only 7% in men. We hope the burden of infection will decrease over time with increased vaccination.”
The researchers noted that their work does not show a cause and effect relationship between their data and the reduction of the prevalence of infection. So while no public health recommendation can be made from the data, Gillison said that if parents choose to vaccinate their children under the current guidelines, there may be additional benefits including a reduced risk of head and neck cancer.
The study will be presented at the American Society of Clinical Oncology’s 2017 Annual Meeting, which takes place from June 2 to June 6 in Chicago.