Having oral sex with more than 10 previous partners was associated with a 4.3 times’ greater likelihood of developing human papillomavirus (HPV)–related oropharyngeal cancer, according to new findings.
The study also found that having more partners in a shorter period (i.e., greater oral sex intensity) and starting oral sex at a younger age were associated with higher odds of having HPV-related cancer of the mouth and throat.
The new study, published online on Jan. 11 in Cancer, confirms previous findings and adds more nuance, say the researchers.
Previous studies have demonstrated that oral sex is a strong risk factor for HPV-related oropharyngeal cancer, which has increased in incidence in recent decades, particularly cancer of the base of the tongue and palatine and lingual tonsils.
“Our research adds more nuance in our understanding of how people acquire oral HPV infection and HPV-related oropharyngeal cancer,” said study author Gypsyamber D’Souza, PhD, professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, Baltimore. “It suggests that risk of infection is not only from the number of oral sexual partners but that the timing and type of partner also influence risk.”
The results of the study do not change the clinical care or screening of patients, Dr. D’Souza noted, but the study does add context for patients and providers in understanding, “Why did I get HPV-oropharyngeal cancer?” she said.
“We know that people who develop HPV-oropharyngeal cancer have a wide range of sexual histories, but we do not suggest sexual history be used for screening, as many patients have low-risk sexual histories,” she said. “By chance, it only takes one partner who is infected to acquire the infection, while others who have had many partners by chance do not get exposed, or who are exposed but clear the infection.”
Reinforces the need for vaccination
Approached for comment, Joseph Califano, MD, physician-in-chief at the Moores Cancer Center and director of the Head and Neck Cancer Center at the University of California, San Diego, noted that similar data have been published before. The novelty here is in the timing and intensity of oral sex. “It’s not new data, but it certainly reinforces what we knew,” he said in an interview.
These new data are not going to change monitoring, he suggested. “It’s not going to change how we screen, because we don’t do population-based screening for oropharyngeal cancer,” Dr. Califano said.
“It does underline the fact that vaccination is really the key to preventing HPV-mediated cancers,” he said.
He pointed out that some data show lower rates of high-risk oral HPV shedding by children who have been appropriately vaccinated.
“This paper really highlights the fact we need to get people vaccinated early, before sexual debut,” he said. “In this case, sexual debut doesn’t necessarily mean intercourse but oral sex, and that’s a different concept of when sex starts.”
These new data “reinforce the fact that early exposure is what we need to focus on,” he said.
Details of the new findings
The current study by Dr. D’Souza and colleagues included 163 patients with HPV-related oropharyngeal cancer who were enrolled in the Papillomavirus Role in Oral Cancer Viral Etiology (PROVE) study. These patients were compared with 345 matched control persons.
All participants completed a behavioral survey and provided a blood sample. For the patients with cancer, a tumor sample was obtained.
The majority of participants were male (85% and 82%), were aged 50-69 years, were currently married or living with a partner, and identified as heterosexual. Case patients were more likely to report a history of sexually transmitted infection than were control participants (P = .003).
Case patients were more likely to have ever performed oral sex compared to control persons (98.8% vs 90.4%; P < .001) and to have performed oral sex at the time of their sexual debut (33.3% of case patients vs 21.4% of control persons; P = .004; odds ratio [OR], 1.8).
Significantly more case patients than control persons reported starting oral sex before they were 18 years old (37.4% of cases vs. 22.6% of controls; P < .001; OR, 3.1), and they had a greater number of lifetime oral sex partners (44.8% of cases and 19.1% of controls reported having more than 10 partners; P < .001; OR, 4.3).
Intensity of oral sexual exposure, which the authors measured by number of partners per 10 years, was also significantly higher among cases than controls (30.8% vs 11.1%; P < .001; OR, 5.6).
After adjustment for confounders (such as the lifetime number of oral sex partners and tobacco use), ever performing oral sex (adjusted odds ratio [aOR], 4.4), early age of first oral sex encounter (20 years: aOR, 1.8), and oral sex intensity (aOR, 2.8) all remained significantly associated with increased odds of HPV-oropharyngeal cancer.
The type of sexual partner, such as partners who were older (OR, 1.7) and having a partner who engaged in extramarital sex (OR, 1.6), were also associated with increased odds of developing HPV-oropharyngeal cancer. In addition, seropositivity for antibodies to HPV16 E6 (OR, 286) and any HPV16 E protein (E1, E2, E6, E7; OR, 163) were also associated with increased odds of developing the disease.
The study was supported by the National Institute of Dental and Craniofacial Research and the National Institute on Deafness and Other Communication Disorders. Dr. D’Souza and Dr. Califano have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.