The human papillomavirus (HPV) has been linked to cervical vulvar, vaginal and anal cancers in women. Almost all cervical cancer is due to HPV with two types, HPV16 and HPV18, accounting for 70 percent of the cases.
Happily, the U.S. Food and Drug Administration has approved HPV vaccines, and they are effective. It is estimated that they may prevent 70 percent of cervical cancer, 80 percent of anal cancer, 60 percent of vaginal cancer, 40 percent of vulvar cancer, and possibly some mouth cancer.
Here's the kicker: HPV is also known to cause cancers in the back of the throat, in an area known as the oropharynx. HPV is linked with about 70 percent of these types of cancers in the U.S. and the rates of these cancers are rising dramatically, according to the Centers for Disease Control and Prevention. But the FDA has not approved the HPV vaccine for prevention of head and neck cancers, because the vaccines have not been evaluated in clinical trials for that purpose.
Enter Dr. Maura Gillison and her research team from the University of Texas MD Anderson Cancer Center. Gillison wondered about using existing data to determine, as she put it, “if there's a potential solution to these rising rates already existing on [drug] shelves."
The scientists examined data from more than 2,600 Americans, aged 18 to 33, who had already received HPV vaccinations. They determined that they were 88 percent less likely to have oral HPV infections than those who were not vaccinated.
Earlier studies had indicated that HPV-related head and neck cancers are more common in men than women, so Gillison and her colleagues studied whether vaccination was associated with a reduced prevalence of oral HPV infection 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 percent," Gillison said.
"We also wanted to determine, accounting for the low rates of vaccination, what proportion of infections could have been prevented," she said.
"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 percent overall, and only 7 percent in men. We hope the burden of infection will decrease over time with increased vaccination," Gillison said.
The research will be presented at the 2017 American Society of Clinical Oncology annual meeting.