Study population

The study population for this cross-sectional analysis was comprised of individuals with no history of head and neck cancer or radiation that were enrolled as age and sex matched clinic controls for a multicenter, case-control study of incident head and neck cancer. Adult patients seeking care at outpatient clinics for Otology, Audiology, and Laryngology between May 2014 to May 2017 for chief complaints that did not include or result in a diagnosis of cancer were eligible for this study. Further eligibility criteria included serum availability, no history of HPV vaccination (6 vaccinated people were excluded as potentially not at risk), and less than 100 oral or vaginal sexual partners (24 people with >100 partners excluded as non-representative). Study sites included Johns Hopkins Hospital (Baltimore, MD), Greater Baltimore Medical Center (Baltimore, MD), University of California – San Francisco Medical Center (San Francisco, CA), and Mount Sinai (New York, NY). Written informed consent was given by all enrollees, and institutional review boards at each study site approved the protocol.