The large-scale meta-analysis of 41 studies* involving over 5,000 women across five continents was the first to investigate whether cervical HPV positivity increases the risk of oral HPV infection.
It shows that oral HPV is significantly more common among women with cervical HPV – 13% compared to 4% in HPV-negative women, translating to a 2.22-fold increased risk.
In addition, 17% of women with both cervical HPV and positive cytology also had oral HPV.
HPV is the world’s most common sexually transmitted infection, affecting an estimated 630 million people and causing about 5% of all cancers, the study, recently published in the Journal of Dental Research, states. While its role in cervical cancer is widely known, HPV is also a major driver of oropharyngeal cancers – particularly in the tonsils and base of the tongue.
“Cervical HPV may be a red flag for broader infection risk,” said Dr Noémi Katinka Rózsa, Director of Semmelweis University’s Department of Paediatric Dentistry and Orthodontics and lead author of the study. “One in eight of these women also carry HPV in the mouth, nearly always without symptoms – while this figure dropped to one in twenty-five among those without cervical HPV.”
HPV is most commonly transmitted sexually through skin and mucosal contact, allowing the virus to travel from the cervix to the mouth. Most often, women who are cervical HPV-positive infect their partners, and are then reinfected through oral sex. In some cases, the male partner may carry HPV from a previous relationship.
Although this study focused on women, men face a higher risk of HPV-related oropharyngeal cancers, with nearly 22,000 overall cases diagnosed each year but rates are four times higher in men than in women. This may be due to higher viral loads in the cervix, exposing heterosexual men to more HPV during oral sex.
There are about 200 HPV types, with over 20 linked to cancer. Almost all sexually active people will contract the virus during their lifetime, but HPV infections are often cleared naturally. However, if the virus persists, it can eventually cause malignant changes and lead to cancer.
Although HPV is best known for causing cervical cancer, it can also lead to increasingly common cancers of the anus, penis, vagina, vulva – and oropharynx, the middle part of the throat behind the mouth.
“We detected the highest oral HPV prevalence in women who were both cervical HPV-positive and had abnormal cytology, which is most often caused by HPV infection. When lesions appear, it suggests that HPV has been present on the cervix for a longer time, likely increasing the chance of spread to the mouth and throat,” explained Dr. Adél Eszter Mózes, a dental PhD student at Semmelweis University and first author of the study.
The researchers warn that while cervical cancer screening programs have drastically reduced cancer rates in high-income countries, HPV-related oropharyngeal cancers are on the rise.
At present, there is no standard screening for oral HPV, and the U.S. Food and Drug Administration (FDA) does not recommend widespread testing due to the lack of a validated tool and low prevalence. However, these new findings show a clear association between cervical and oral HPV infection, suggesting that prevalence may not be so low in specific at-risk groups.
“Currently, the absence of a clear oral and oropharyngeal lesion that precedes HPV-related throat cancers makes early detection extremely difficult.
But identifying women with cervical HPV as a high-risk group could open new pathways for prevention, including closer monitoring and referral to Ear, Nose and Throat (ENT) specialists or dentists,
added Dr Mózes.
Without reliable oral HPV tests, vaccination remains the main prevention.
“HPV vaccination offers up to 90% protection against the virus for at least 15 years, including the types most likely to cause cancer. However, global vaccine uptake is still below targets, and public awareness remains low,” – adds Dr Nándor Ács, Director of the Department of Obstetrics and Gynaecology, co-author of the study.
The first HPV vaccine was approved in 2006, and in 2020, the FDA expanded the use of the vaccine that protects against the nine most dangerous HPV strains to prevent oropharyngeal and other head and neck cancers. However, herd immunity is still distant, with vaccination coverage in WHO regions ranging between 29% and 60%, well below the 80-90% target.
High-risk cervical HPV infections are asymptomatic with no signs until changes are detected by screening, highlighting the importance of regular HPV testing and Pap smears.
* All studies in the meta-analysis met strict criteria, such as testing for the nine genotypes covered by the most used HPV vaccine, which protects against the most dangerous strains of the virus.
Photo: Boglarka Zellei, Attila Kovacs – Semmelweis University; Cover photo (illustration): Envato Elements – chormail
