Number of Sexual Partners, Smoking Identified as Risk Factors for Oropharyngeal Cancer

Carole Fakhry, MD

While the incidence of HPV-related oropharyngeal cancer (HPV-OPC) is increasing, the risk for developing the disease remains low for most people.

Investigators at Johns Hopkins University have determined that, among men aged 50 to 59 years, 8.1% have an oncogenic oral HPV infection and 2.1% have an oral HPV16 infection, but only 0.7% will ever develop oropharyngeal cancer in their lifetime. Current smokers and men who have had at least fife lifetime oral sex partners were at elevated risk, with a lifetime prevalence of 14.9%.

"Despite recent increases in its incidence, HPV-associated oropharyngeal cancer remains a rare cancer in the United States," coauthor Carole Fakhry, MD, an associate professor in the Johns Hopkins School of Medicine and Bloomberg School's Department of Epidemiology, said in a press release.

About 70% of oropharyngeal cancers are related to HPV. According to the Centers for Disease Control and Prevention, roughly 12,000 people are diagnosed with HPV-associated cancers annually. The incidence of HPV-associated oropharyngeal cancer has been rising since the 1980s, and in the past 2 decades has doubled among men.

To determine which patients were most likely to develop HPV-associated oropharyngeal cancers, Fakhry et al examined data from 13,089 people aged 20 to 69 years who participated in National Health and Nutrition Examination Survey (NHANES) from 2009 to 2014 and had oral HPV DNA testing. Participants aged 20 to 59 (n = 9425) were analyzed for number of oral sex partners. To assess projections of OPC risk, investigators reviewed Incidence and incidence-based mortality data from SEER 18 registries from 2009 to 2014 along with National Center for Health Statistics mortality data.

Oral infections with HPV types known to cause oropharyngeal cancer—especially HPV16, which causes most throat cancers—were present at low prevalence in every defined group in the study. However, men were far more likely to be positive for the presence of HPV DNA. Women aged 20 to 69 had a frequency of infection of just over 1% compared with 6% for men aged 20 to 69.

Investigators explored oncogenic oral HPV prevalence by sex, sexual behavior, and tobacco use to better understand groups that have higher and lower prevalence. Prevalence is particularly low among both men and women who have never performed oral sex (<2.5%). However, prevalence increased with number of lifetime oral sexual partners, up to 14.4% in men aged 20 to 59 years with ≥10 lifetime oral sexual partners.

Regardless of what other risk factors participants had, oncogenic oral HPV prevalence was low among those with ≤1 lifetime oral sexual partner (0.7% for women and 1.7% for men). Prevalence doubled among women with ≥2 lifetime oral sexual partners versus those with 0 to 1 (1.5% vs 0.7%; P = .02), but remained low among women with a higher number lifetime oral sexual partners.

Prevalence was highest among men who currently smoked and had ≥5 lifetime oral sexual partners (14.9%; 95% CI, 11.4—19.1). Men with only 1 of these risk factors (ie, either smoked and had 2 to 4 partners or did not smoke and had ≥5 partners) were at intermediate risk, with an oncogenic oral HPV prevalence of 7.3% (95% CI, 5.8-9.1). Findings were similar when investigators considered oral HPV16 infection specifically.

Infection with any potentially cancer-causing HPV type is not necessarily predictive, in part because some HPV types are much more cancer-causing than others. HPV16 is thought to cause more than 90% of all HPV-driven oropharyngeal cancers, but the NHANES data showed that prevalence was very low on average in all groups, ranging from 0.1% in women aged 60 to 69 years to 2.4% in men aged 60 to 69.

Study co-author Gypsyamber D'Souza, PhD, an associate professor in the Bloomberg School's departments of Epidemiology and International Health, cautioned against mass screening for oral HPV infection. She noted that existing tests for HPV can cause more harm from false positives than benefits.

"For most people, these data should be very reassuring, as they show that their risk of oropharyngeal cancer is very low,” she said in a press release. “Currently available tests for the presence of oral HPV infections are not very predictive of oropharyngeal cancer risk—most people who have an oral HPV infection will eventually clear it on their own.”

D’Souza G, McNeel TS, Fakhry C. Understanding personal risk of oropharyngeal cancer: risk-groups for oncogenic oral HPV infection and oropharyngeal cancer [published online October 19, 2017]. Ann Oncol. doi:10.1093/annonc/mdx535.