Smoking and oral sex are associated with an increased risk of developing HPV-related oropharyngeal cancer.
The risk of developing the condition was found to be considerably lower among women, non-smokers, and those who had had fewer than five partners with whom they had performed oral sex.
Prof. Gypsyamber D'Souza, of the Johns Hopkins Bloomberg School of Public Health, and Dr. Carole Fakhry, of the Johns Hopkins Department of Otolaryngology-Head and Neck Surgery — both of which are located in Baltimore, MD — conducted the research. Their results have been published in the journal Annals of Oncology.
Every year in the United States, there are approximately 16,500 cases of oropharyngeal squamous cell carcinoma, which is the most common type of oropharyngeal cancer. More than 11,500 of these are HPV-related.
More than 100 different types of HPV exist, but only a few of these are known to cause cancer. HPV16 or 18, for example, triggers most cases of cervical cancer, and HPV16 is known to cause most oropharyngeal cancers.
Experts have predicted that by 2020, the incidence of oropharyngeal cancer will overtake that of cervical cancer.
"For these reasons," says Prof. D'Souza, "it would be useful to be able to identify healthy people who are most at risk of developing oropharyngeal cancer in order to inform potential screening strategies, if effective screening tests could be developed."
She adds, "Most people perform oral sex in their lives, and we found that oral infection with cancer-causing HPV was rare among women regardless of how many oral sex partners they had."
"Among men who did not smoke," Prof. D'Souza says, "cancer-causing oral HPV was rare among everyone who had less than five oral sex partners, although the chances of having oral HPV infection did increase with number of oral sexual partners, and with smoking."
The study data came from 13,089 individuals, all of whom were aged 20–69 years old, who took part in the National Health and Nutrition Examination Survey.
The participants had all been tested for oral HPV infection. To predict the risk of oropharyngeal cancer from oral HPV infection, the researchers used data on oropharyngeal cancer cases and deaths from U.S. registries.
Smoking and oral sex partners elevate risk
Prof. D'Souza and Dr. Fakhry found the lowest prevalence of oral infection with cancer-causing forms of HPV in women who had had one or no oral sex partners during their lifetimes.
Of these, 1.8 percent were smokers and 0.5 percent were non-smokers. The risk of infection climbed slightly to 1.5 percent for women who had had two to more oral sex partners.
Among men, those who had had one or no oral sex partners were at the lowest risk, with a prevalence of 1.5 percent for oral HPV infection. Among men with two to four oral sex partners, prevalence increased to 4 percent among non-smokers and elevated further to 7.1 percent among men who smoked.
Non-smoking men who had had five or more oral sex partners had a prevalence of oral HPV infection of 7.4 percent. The highest prevalence of infection — reaching 15 percent — was observed among men with five or more oral sex partners and who smoked.
"Currently, there are no tests that could be used for screening people for oropharyngeal cancer," explains Dr. Fakhry. "It is a rare cancer, and for most healthy people the harms of screening for it would outweigh the benefits because of the problem of false positive test results and consequent anxiety."
"Our research shows that identifying those who have oral HPV infection does not predict their future risk of cancer well, and so screening based on detecting cancer-causing oral HPV infection would be challenging."
Dr. Carole Fakhry
"However," she adds, "we are carrying out further research of oral HPV infection in young healthy men to explore this further."
Dr. Fakhry continues to say that current research is analyzing different biological markers, and some of them could potentially be used for screening for oropharyngeal cancer in some people.
"Some studies suggest people who have antibodies against cancer-causing types of HPV have an increased risk of HPV-related cancer, but these antibodies are very rare," says Dr. Fakhry.
"Therefore," she concludes, "it is not yet clear whether they will be useful for screening. Presently, these tests are not commercially available, and are still in research labs only."