Abstract
BackgroundHuman papillomavirus (HPV) infection, particularly with type 16, causes a growing fraction of oropharyngeal cancers, whose incidence is increasing, mainly in developed countries. In a double-blind controlled trial conducted to investigate vaccine efficacy (VE) of the bivalent HPV 16/18 vaccine against cervical infections and lesions, we estimated VE against prevalent oral HPV infections 4 years after vaccination.Methods and FindingsA total of 7,466 women 18–25 years old were randomized (1∶1) to receive the HPV16/18 vaccine or hepatitis A vaccine as control. At the final blinded 4-year study visit, 5,840 participants provided oral specimens (91·9% of eligible women) to evaluate VE against oral infections. Our primary analysis evaluated prevalent oral HPV infection among all vaccinated women with oral and cervical HPV results. Corresponding VE against prevalent cervical HPV16/18 infection was calculated for comparison. Oral prevalence of identifiable mucosal HPV was relatively low (1·7%). Approximately four years after vaccination, there were 15 prevalent HPV16/18 infections in the control group and one in the vaccine group, for an estimated VE of 93·3% (95% CI = 63% to 100%). Corresponding efficacy against prevalent cervical HPV16/18 infection for the same cohort at the same visit was 72·0% (95% CI = 63% to 79%) (p versus oral VE = 0·04). There was no statistically significant protection against other oral HPV infections, though power was limited for these analyses.ConclusionsHPV prevalence four years after vaccination with the ASO4-adjuvanted HPV16/18 vaccine was much lower among women in the vaccine arm compared to the control arm, suggesting that the vaccine affords strong protection against oral HPV16/18 infection, with potentially important implications for prevention of increasingly common HPV-associated oropharyngeal cancer.ClinicalTrials.gov, Registry number NCT00128661
Highlights
A subset of oropharyngeal cancers (OPC) is caused by human papillomavirus (HPV) infection [1], with strong predominance of HPV16, which is detectable in about 90% of Human papillomavirus (HPV)-positive cases [2]
HPV prevalence four years after vaccination with the ASO4-adjuvanted HPV16/18 vaccine was much lower among women in the vaccine arm compared to the control arm, suggesting that the vaccine affords strong protection against oral HPV16/18 infection, with potentially important implications for prevention of increasingly common HPVassociated oropharyngeal cancer
Ethics Statement The protocol for this trial and supporting CONSORT checklist are available as supporting information; see Checklist S1 and Protocol S1.The trial was approved by institutional review boards of the National Cancer Institute in the US and the Instituto Costarricense de Investigacion y Ensenanza en Nutricion y Salud (INCIENSA) in Costa Rica, and all participants signed IRBapproved consent forms
Summary
A subset of oropharyngeal cancers (OPC) is caused by human papillomavirus (HPV) infection [1], with strong predominance of HPV16, which is detectable in about 90% of HPV-positive cases [2]. HPV-positive OPC constitutes a distinct clinico-pathological entity with risk factors different from those for HPV-negative tumors. The authors estimated that in the few decades, in the US, there will be more cases of HPV-positive OPC than of cervical cancer, where virtually all cases are attributable to HPV. In a report from Stockholm, Sweden [10], the incidence rate of HPV positive tonsillar cancers nearly doubled each decade between 1970 and 2007, while HPV negative tumors declined, leading the authors to suggest an epidemic of viral-induced carcinomas. Human papillomavirus (HPV) infection, with type 16, causes a growing fraction of oropharyngeal cancers, whose incidence is increasing, mainly in developed countries. In a double-blind controlled trial conducted to investigate vaccine efficacy (VE) of the bivalent HPV 16/18 vaccine against cervical infections and lesions, we estimated VE against prevalent oral HPV infections 4 years after vaccination
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