A rise in oral sex may be pushing up
HPV infection rates in men, along with head and neck
Oral infections of human
papillomavirus, or HPV, affect nearly 7% of Americans and are significantly
more common in men than in women, according to a new Centers for Disease
Control and Prevention study.
The study, which is the first to
examine the prevalence of oral HPV in the U.S., found that three times as many
men (10%) as women (3.6%) have HPV infections. The data may help to explain why
the incidence of head and neck cancers has been increasing, particularly in
males, even as smoking rates are on the decline.
For the study, CDC researchers
plumbed data on 5,579 people aged 14 to 69 who participated in the National
Health and Nutrition Examination Survey in 2009 and 2010. The participants
answered extensive questionnaires about their sexual behavior and gave oral cell
samples for analysis for HPV.
The researchers found that the risk
of oral HPV infection increased with the number of sexual partners a person
had: it was eight times higher in people who had ever had sex versus not, and
as high as 20% in people who had had more than 20 sexual partners in their
lifetime. The data indicate that “oral HPV infection is predominantly sexually
transmitted,” through oral sex, not passed through casual contact like kissing,
the authors concluded.
The CDC researchers also found that
HPV infections peaked in two age groups: 30-to-34-year-olds, who had a 7.3%
chance of infection, and 60-to-64-year-olds, who were 11.4% likely to be
infected. It’s not clear why older people had higher rates of oral HPV, but the
authors offered some possible theories: perhaps it’s because older people came
of age at a time when there were fewer concerns about sexually transmitted
infections, or perhaps latent HPV infections are becoming reactivated as the
immune system weakens with age.
HPV is the most commonly sexually
transmitted virus in the U.S. At least half of all sexually active people will
acquire an infection at some point in their lives. Most will clear the virus on
their own, but persistent infections can cause cancer, including cervical,
vulvar, vaginal, anal and penile cancers. Oral infection with a high-risk
strain of HPV can cause oropharyngeal cancers — cancers of the tonsils, upper
throat and base of the tongue.
Rates of oral HPV infection are
substantially lower than genital infections — which can be as high as 42% in
women in their 20s, for example — but they are becoming increasingly
troublesome. While HPV is best known as the virus that causes cervical cancer
in women, because of better screening, the rate of such cancers has declined.
Meanwhile, the rate of oral cancers is on the rise: a study published in
October in the Journal of Clinical Oncology found that HPV-related oropharyngeal cancers
increased 225% between 1984-89 and 2000-04. In 1984-89, about 16% of
oropharyngeal cancers tested HPV-positive; by 2000-04, the proportion of
HPV-positive cancers had risen to 72%, accounting for more oral cancer than
smoking.
Overall, the risk was greatest and
rising in men, the study found, possibly because of increasing rates of oral
sex. The data indicate that the burden of HPV-related cancer may shift from
women to men, with the number of HPV-positive oral cancers potentially
eclipsing that of invasive cervical cancers within 10 years.
That supports efforts to boost HPV
vaccination, suggest the authors of the current CDC study, published online by the Journal of the
American Medical Association. Public health officials recommend that girls aged 11 or 12 be immunized
with either of two approved HPV vaccines, Gardasil or Cervarix, which both
protect against HPV 16 and 18, the strains that cause most cervical cancers.
(Gardasil also protects against HPV strains 6 and 11, which cause 90% of
genital warts cases.) Girls aged 13 to 26 should also be immunized if they
haven’t been already.
The advice extends to boys as well, but only one of
the shots, Gardasil, has been tested and approved for males to protect against
warts and anal cancer. Boys are advised to receive the vaccine at age 11 or 12,
or between ages 13 and 21 if they haven’t already been immunized. The primary
reason for the advice is to protect adolescents and young adults from infection
with the high-risk strains of cancer-causing HPV before they become sexually
active.
It’s not clear whether the vaccines
can also protect against oral cancers. More research is needed to figure that
out. But researchers speculate that if the vaccine reduces rates of HPV in
women, it can in turn help reduce the risk of infection in men.
Dr. Caroline Wallace DDS
Complete Dental Care
Salem, Virginia
Americans need a serious
brush-up when it comes to their oral health. On average, Americans scored
a "D" on a series of questions such as how often to brush, what age a
child should first visit a dentist and what causes cavities.
