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Journal Club: First cervical, now oropharyngeal – the link between HPV and carcinoma
Nov 15, 2012 by Jessica Wilford, UBC Dermatology PGY2
Gillison ML, Broutian T, Pickard RK, et al. Prevalence of oral HPV infection in the united states, 2009-2010. JAMA. 2012;307(7):693-703.
Purpose of the study
The goal of this study was to estimate the prevalence of oropharyngeal squamous cell cancer (OSCC) in the US. There are 500,000 cases of OSCC per year worldwide, and classical risk factors include smoking, smokeless tobacco, betel nut chewing, and alcohol consumption.
However, many patients with OSCC, especially at the base of the tongue and in the tonsillar region, do not display these risk factors. In these patients, HPV-16 is often a causative agent (along with, to a lesser extent, HPV-18, 31, 33). HPV now accounts for more than one-half of OSCC in the United States and Western Europe. HPV-associated OSCC affect younger patients without a history of excessive exposure to alcohol and tobacco, and HPV-positive OSCCs are associated with sexual behaviour.
This study was a population-based survey of oral HPV prevalence conducted within the US National Health and Nutrition Examination Survey (NHANES) from 2009 to 2010. The study consisted of a household interview followed by physical examination and interviews at a mobile examination center, and approximately 5000 subjects participated. Participants performed a swish and spit of Scope or saline into sterile collection cups, and then PCR analysis identified which, if any, HPV strains were present.
The findings resulted in an estimate of the overall prevalence of oral HPV in the US population of 6.9%. The prevalence of high-risk HPV was 3.7%, and the prevalence of HPV-16, the most common high-risk type, was 1.0%.
The results demonstrated two age peaks for high-risk HPV, in the early thirties and early sixties, and the male prevalence, at 10.1%, was greater than the female prevalence of 3.6%. This sex difference persisted even after controlling for other factors. Men also demonstrated greater HPV-16 prevalence than women, at 1.6% vs. 0.3% respectively. HPV was more prevalent among smokers, heavy drinkers, and marijuana uses, and the correlation between smoking and oral HPV was stronger among women. The age peaks were not clearly explained by this study, and a contributing factor could be the exclusion of some sexual behaviour questions for subjects over age 59.
Oral HPV infection was strongly correlated with ever having had sex (7.5% vs 0.8%), and HPV prevalence increased with increasing number of partners - of people with more than 20 lifetime partners, 20% were infected with HPV. Infection rates were higher when first oral sex was performed at age 18 or younger. However, increasing prevalence was associated with any sexual behavior, not just oral sex, which raises questions about transmission.
Impact on clinical practice
This study provides data on the population prevalence of oral HPV, however now natural history studies are required to better understand the effects of age, sex, and modifiable risk factors on incidence and duration of HPV infection. Areas that may be illuminated by future research include:
- The relationship between smoking and HPV-positive OSCC
- Whether targeted secondary prevention of OSCC is possible based on similarities between age- and sex-related HPV and OSCC incidence
- Efficacy of HPV vaccine against oral HPV
By 2020, it is estimated HPV-positive OSCC will surpass the incidence of invasive cervical cancer. Further data will likely have a large impact on clinical practice regarding prevention and detection of oral HPV and OSCC.
Dr. Richard Lester, Medical Head, STI/HIV Control, Clinical Prevention Services, BCCDC
Haddad, RI. Human papillomavirus associated head and neck cancer. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2012.
Kreimer AR, Villa A, Nyitray AG, et al. The epidemiology of oral HPV infection among a multinational sample of healthy men. Cancer Epidemiol Biomarkers Prev. 2011;20(1):172-182.
Categories: Journal club