Reports of an increase in head and neck cancers that are caused by human papillomavirus, or HPV, have lead some to propose that changes in sexual behavior, specifically an increase in oral sex, are responsible.
But experts say such conclusions may be premature, or at least overstated, and are leading to unnecessary worry.
While oral sex may be a risk factor for some types of head and neck cancer, the link is, at this point, speculative, experts say. Moreover, there are many other elements that play a role in whether a person develops cancer, including the strength of the immune system, said Sara Rosenquist, a psychologist and sex therapist in North Carolina.
In general, there is no need for individuals in monogamous relationships to restrict their sexual activities if the pair is in good health, Rosenquist said.
Rosenquist recently wrote an article in the Journal of Sexual Medicine to dispel myths about oral sex and cancer.
First, Rosenquist notes cases of head and neck cancer are not increasing. As a group, cases of this cancer have actually declined in the United States over the past 25 years. However, there has been in increase in the proportion of head and neck cancers caused by HPV, primarily among younger individuals.
HPV is thought to be, for the most part, sexually transmitted. The viruses cause almost all cases of cervical cancer, and can cause genital warts and anal cancer. The link between HPV and oral cancers is less clear.
Oral sex has been linked with an increased risk of acquiring an HPV infection in the mouth, and with an increased risk of developing oral cancers that are caused by HPV. But sex in general has also been linked with these risks.
A study published this year in the Journal of the American Medical Association (JAMA) found people who reported engaging in oral sex were twice as likely to have an oral HPV infection as those who did not engage in oral sex. But people who reported having sex of any kind were eight times more likely to have an oral HPV infection than those who had not had sex.
"There are no data to directly support a link between changes in sexual behavior and increased incidence of HPV-associated cancer, because the data do not exist," Dr. Maura Gillison, chair of cancer research at Ohio State University who has studied HPV, told MyHealthNewsDaily in an email.
An HPV infection becomes concerning if it persists in the body for a long time, as persistent HPV infections are more likely to cause cancer, Rosenquist said. And persistent infections occur when the body's immune system can't clear the virus. So any factors that would compromise the immune system function may increase cancer risk.
The more sexual partners a person has, the more swamped their immune system becomes, Rosenquist said. So if any sexual behavior change is responsible for the uptick in oral cancers caused by HPV, it's an increase in promiscuity, not oral sex, Rosenquist said.
The JAMA study found that among teens and adults who'd had 20 or more sexual partners in their lifetimes, one in five had an oral HPV infection. Another study found that people who had performed oral sex on six or more partners in their lifetime had an eightfold increased risk of cancers of the mouth or throat.
If you are in a monogamous relationship and have had fewer than six sexual partners in your lifetime, chances are "that you and your partner will be swapping HPV back and forth, with infections waxing and waning over your lifetime," Rosenquist said.
If you are able to clear HPV, but your partner is not, you may both be at risk of a persistent infection, Rosenquist said. A 2006 study found that the presence of a persistent HPV infection in one partner in a relationship increased the risk of a persistent infection in the other partner tenfold.
HPV should not be a concern for monogamous couples if there is no sex outside the relationship and they do not encounter factors that could comprise the immune system, Rosenquist said.
"Sexually active adults are more likely to benefit from healthy lifestyles that promote good immune functioning coupled with regular medical checkups aimed at early detection and treatment," Rosenquist said.
Rosenquist also advises couples to stop worrying, as worry and stress may also reduce immune system strength.
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