Diagnosing HPV at the dentist

From the Vaccine and Infectious Disease Division and the University of Washington

Human papillomavirus (HPV)-associated oropharyngeal cancer incidence is on the rise in the United States, especially in men. HPV strains 16 and 18 have been identified as the primary risk factor for these cancers, but routine screening for oral HPV16 and 18 is currently not recommended despite the availability of commercial qualitative and quantitative HPV tests. However, oral HPV diagnostics could potentially be performed during routine dental cleaning visits, providing a non-invasive screen that may identify persons at increased risk of future oropharyngeal cancer.  In 2016, several Seattle-area dental clinics begun to offer HPV 16 and 18 oral screens during routine visits, but HPV diagnostics conducted via oral washes at dental clinics have not been validated on a large scale. To   understand better how to interpret the positive HPV results, Dr. Helen Stankiewicz Karita, a physician at the University of Washington, along with collaborators from the University of Washington and Fred Hutch, used samples collected from these visits to investigate the prevalence of oral HPV16 and 18 and to assess quantitative HPV16 and 18 detection in oral rinses. They recently published this work in Sexually Transmitted Diseases.

The authors took advantage of the 15,000 oral rinses collected from dental patients who elected to test and measured viral load through an established and validated HPV16/18 PCR. Of these patients, one percent resulted in oral washes positive for HPV 16 or 18, with a higher prevalence in men than women, as has been previously reported. HPV16/18 prevalence increased with age in men but not in women, suggesting a sex-dependent association between increased age and HPV16/18 risk. Additionally, 628 people contributed two oral rinses, six months apart, and those with a higher baseline HPV viral load were more likely to have persistent HPV16/18 at follow up, while a lower baseline viral load was associated with clearance of the virus at the second visit. Together, these results suggest that oral rinsesperformed at routine dental visits  could be used to non-invasively screen for cancer-causing HPV16/18 and that patients are interested in oral HPV testing while receiving routine teeth cleanings.

HPV16/18 viral load in oral rinses.
Figure provided by Dr. Stankiewicz Karita

Oral  sampling for HPV could provide an important cancer screening tool, as the secondary screening methods  used to detect  lesions that are precursors to cervical cancer  have not been identified for oral HPV-associated cancers.   The authors also posit that this screening method could be used to confirm complete removal of oral tumors, as published work showed that HPV16 detection is rare following tumor ablation.

Following the success of this early study, “future directions in this field should include robust long-term natural history studies from the detection of infection to oncogenic transformation to elucidate the risk factors for persistent infection and progression to cancer,” Stankiewicz explained. “We found that a small percentage of men had persistently high amounts of oral HPV detected in two consecutives rinses and we are currently designing new studies to evaluate their clinical characteristics and viral dynamics,” she continued. Dr. Wald added that the authors “wonder if the use of the current HPV vaccine could alter the natural course of infection in those persons” and hope to answer this question in the future.  

This work was supported by the University of Washington Sexually Transmitted Infections Cooperative Research Center,  the National Cancer Institute; the HPV testing was performed by Fidalab.

Fred Hutch/UW Cancer Consortium members Anna Wald and Keith Jerome contributed to this work.

Stankiewicz Karita HC, Magaret A, Huang ML, Jerome KR, Feng Q, Wald A. 2020. Quantitative Oral HPV16 and HPV18 Detection in Persons Attending Dental Clinics. Sexually Transmitted Diseases. 2020 Feb;47(2):100-104. doi: 10.1097/OLQ.0000000000001097.