Nearly 45 percent of patients had more than 10 sexual partners during their lives, compared with 19 percent of controls without cancer. People under 23 who had a sexual partner at least 10 years older were more likely to be infected, possibly because older people had a longer exposure to the virus.
The deep kiss was also associated with an increased risk. Those who had 10 or more partners who kissed deeply were twice as likely to have HPV-related cancer as those who had none or one.
People who reported that their partners had extramarital affairs, and those who even suspected their partners had affairs, also had an increased risk of HPV-associated throat cancer. There was no association of HPV-related throat cancer with smoking, alcohol consumption or substance use.
The study had limitations. It depended on self-reports, which are not always reliable, and since more than 95% of participants called themselves heterosexuals, there was insufficient data to draw conclusions about the effects of sexual orientation on HPV and the risk of cancer. But the analysis carefully combined controls, HPV tumor data and a confidential questionnaire, all contributing to its strengths.
Dr. Jason D. Wright, associate professor of gynecological oncology at Columbia University, who was not involved in the research, believes the work can be useful in clinical practice. “This is one of the first studies to provide detailed details to patients about how specific practices influence long-term risk,” he said. “Greater exposure, more partners, oral sex in the beginning – 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 resident physician at Johns Hopkins, said it can be difficult to explain the infection to patients. “If people get this infection, they will ask, ‘Why me?'”, She said. “We don’t know how that information is going to change things clinically. But we can give patients a better understanding of the disease process and how someone contracts it.
Still, she said: “It is complex, more complex than just the number of sexual partners. We don’t have the exact answers on this and we are still discovering the full picture. “