Recent studies indicate that the incidence of oropharyngeal cancers increased more than 200% in the US between 1988 and 2004. As the most common sexually transmitted infection in adolescent and young adult women, human papillomaviruses (HPV) are responsible for nearly all cervical cancers and most anal and oropharyngeal cancers. For a study published in JAMA Network Open, Nicolas Schlecht, PhD, Angela Diaz, MD, PhD, Robert Burk, MD, and colleagues sought to assess the risk factors for oral HPV, as well as the association of HPV vaccination with HPV prevalence in the oral cavity, in sexually active female adolescents receiving the quadrivalent (4vHPV) vaccine.

The researchers tested for HPV DNA through an oral rinse among more than 1,200 women who participated in repeated collection of oral rinse specimens over 10 years. Participants at time of enrollment were aged 13 to 21 (median age, 18) and planning to or already had received the HPV vaccine. Upon entry in the study, participants were asked about sexual behaviors, including number and type of sexual partners. Study authors also collected data on other sexually transmitted diseases, pregnancies, short- and long-term contraceptive use, tobacco smoking, and alcohol, marijuana, and other drug use. Follow-up visits occurred every 6 months until age 25 to obtain samples for HPV testing, and self-reported sexual history questionnaires. DNA from samples was tested for more than 40 types of HPV associated with infecting mucosal tissue.


HPV Numbers

Among participants, the average age of first sexual activity was 14. At the time of enrollment, 69.7% had at least three sexual partners. The HPV detection rate from initial oral rinse samples was 6.2%; 1.7% were oncogenic types and 0.2% were 4vHPV types. “While our study population had a higher average number of sexual partners and an earlier sexual debut on average compared with participants in previous studies, detection of 4vHPV vaccine types (HPV types 6, 11, 16, 18) was significantly lower among vaccinated women when compared with unvaccinated women,” explains Dr. Schlecht. The highest prevalence of oral HPV detection was at age 16 (10.5% for all types, 3.9% for oncogenic types). “The majority of oral HPV that was detected was cleared within 12 months, reflecting the transient nature of these infections,” adds Dr. Schlecht.

Detection of an HPV infection in the cervix increased the tendency for HPV identification in the oral cavity. Although no significant association was seen between giving or receiving oral sex and HPV detection, a strong connection was seen between years of sexual activity and HPV detection.


Prevalence of Vaccination & Infection

When enrolled, 15.3% of participants had not received the 4vHPV vaccine. To compare vaccinated versus unvaccinated participants, Dr. Schlecht and colleagues used a multivariable logistic regression approach, adjusting for years since first sexual activity and concurrent detection of 4vHPV types in the cervix (Table). Participants who had received at least one dose of the 4vHPV vaccine were 83% less likely to have a 4vHPV type detected in the oral cavity compared with unvaccinated participants.

“These findings parallel our earlier observations with cervical and anal HPV,” notes Dr. Schlecht. “Detection of HPV in the oral cavity is not uncommon in sexually active adolescent females, but decreases with age and time since onset of sexual activity. Continued research is needed to determine whether the additional types targeted by the new 9-valent vaccine will also decrease, and whether vaccination reduces the incidence and persistence of oral HPV vaccine types. Similar studies in adolescent males are also needed.”