The first clinical trial to investigate the effectiveness of human papillomavirus vaccination against oral infections suggests that the vaccine prevents such infections, which can promote head and neck cancers. However, the trial was not originally planned to investigate the possible connections to head and neck cancers, and researchers caution that whether the vaccine cuts the risk for these cancers remains to be determined.

The first clinical trial to investigate the effectiveness of human papillomavirus (HPV) vaccination against oral infections suggests that the vaccine prevents such infections, which can promote head and neck cancers. However, researchers caution that whether the vaccine cuts the risk of these cancers remains to be determined.

Oropharyngeal cancers triggered by HPV, particularly by the high-risk subtypes 16 and 18, have surged in recent decades. In 2011, a study led by Maura Gillison, MD, PhD, of Ohio State University in Columbus, reported that the incidence of oropharyngeal cancers testing positive for HPV increased by 225% between 1988 and 2004 (J Clin Oncol 2011;29:4294–301). Although researchers have found that HPV vaccination curbs infections and precancerous lesions at several body sites, including the cervix, they lack comparable data for the oropharynx.

The new work is an offshoot of a large project designed to gauge how well vaccination guards against HPV infections and precancerous lesions in the cervix. More than 7,000 women in Costa Rica received either a vaccine against HPV subtypes 16 and 18 (Cervarix; GlaxoSmithKline) or a control vaccine against hepatitis A. After the study had begun, the organizers decided to test for oral infections and obtained samples of oropharyngeal cells from nearly 6,000 of the participants.

“What is striking is that there seems to be a strong effect of the vaccine,” says lead author Rolando Herrero, PhD, of the International Agency for Research on Cancer in Lyon, France. Four years after the injections, only one of the more than 2,900 women who received the HPV vaccine showed an oral HPV infection, whereas 15 of the more than 2,900 subjects in the control group did. That's a 93% lower incidence in the HPV-vaccinated group, the team reported (PLoS ONE 2013;8:e68329).

Stephen Goldstone, MD, of the Icahn School of Medicine at Mount Sinai in New York, NY, who wasn't involved with the research, says the study has “a clear-cut positive result.” Because the researchers didn't set out to test the vaccine's effects against oral infections, they couldn't determine if any subjects already had such infections at the beginning of the study. That means the vaccine could be even more potent than the results indicate, Goldstone says.

Ohio State's Gillison, who also didn't participate in the Costa Rica study, notes that researchers still need to determine whether preventing HPV oral infections forestalls oropharyngeal cancer. “It's a very good study, but it falls short of being able to make public policy recommendations,” she says.

For more news on cancer research, visit Cancer Discovery online at http://CDnews.aacrjournals.org.

©2013 American Association for Cancer Research.
2013