Almost 45 percent of patients had more than 10 sexual partners in their lifetime, compared to 19 percent of the cancer-free controls. People under the age of 23 who had a sexual partner at least 10 years older were more likely to be infected, possibly because older people had been exposed to the virus for longer.
Deep kissing was also associated with an increased risk. Those who had 10 or more deep kissing partners were more than twice as likely to have HPV-related cancer than those who didn’t have one or none.
People who reported their partners had extramarital affairs, and those who even suspected their partners had affairs, were also at increased risk of HPV-associated larynx cancer. There was no association between HPV-related throat cancer, smoking, alcohol consumption, or substance use.
The study had limitations. It depended on self-reports, which are not always reliable. With more than 95 percent of participants calling themselves heterosexual, there wasn’t enough data to draw conclusions about the effects of sexual orientation on HPV and cancer risk. However, the analysis had compiled carefully matched controls, HPV tumor data, and a confidential questionnaire, all of which add to its strengths.
Dr. Jason D. Wright, Columbia Associate Professor of Gynecological Oncology who was not involved in the research, believes the work could be useful in clinical practice. “This is one of the first studies to give patients detailed information about how certain practices affect their long-term risk,” he said. “Higher exposure, more partners, oral sex early – all of these are risk factors. These are important things to think about when talking to patients. “
The lead author, Dr. Virginia E. Drake, a health care professional at Johns Hopkins, said the infection can be difficult to explain to patients. “When people get this infection, they’ll ask, ‘Why me?'” She said. “We don’t know how this information will change things clinically. But we can give patients a better understanding of the disease process and how someone gets it. “
Still, she said, “It’s complex, more complex than just the number of sexual partners. We don’t have the exact answers to this and are still finding out the full picture. “