HPV and cancer risks for men.
Credit: Photograph by Guido Vitti
Another mystery is why men are three times as likely as women to develop HPV-related oral cancer, although many researchers suspect hormonal differences account for gender discrepancies. Men are more likely than women to have active HPV infections, but they also tend to have lower immune responses to the virus. What's more, as women age, they are less likely to harbor active infections, while older men seem to be just as able as younger men to contract the virus. Another theory has to do with sexual anatomy: Vaginas may spread HPV into the mouth more readily than ­penises, since vaginas usually contain more fluids, in which HPV particles can reside, than the penile shaft or scrotum, the surfaces most involved in oral sex. (Whether HPV resides in semen is still unknown.)

A more worrisome mystery is whether there is a link between HPV and heart disease. A recent study found that women with HPV are two to three times as likely as uninfected women to have had a heart attack or stroke at some point in their lives. It's not clear whether HPV increases the risk of cardiovascular problems or whether women with heart ailments are more likely to contract HPV.

While there is no treatment for HPV infection, two vaccines – Merck's Gardasil and GlaxoSmithKline's Cervarix – protect against HPV-16, the strain associated with oral cancer. But the vaccines have been proved to work only in those not yet exposed to the virus, and only Gardasil is approved for use in males. In 2006, the CDC recommended that girls and young women under age 26 be vaccinated; in October of this year, the agency also advised that all 11- and 12-year-old boys be vaccinated, as well as males ages 13 through 21 who have not had the vaccine's routine course of three shots (which very few have had). "The reason vaccination is important is that we can't distinguish between people who will develop cancer as a result of an HPV infection and those who will not," Gillison says.

Although most major health organizations see vaccination as a medical necessity, it's considered controversial, largely because the cancer it prevents results from sexual activity. The vaccines are also expensive: Gardasil usually costs more than $300 for all three shots. In part for these reasons, fewer than half of girls ages 13 to 17 have received at least one shot, and fewer than a third have received all three required doses. Only about one percent of boys have received the HPV vaccine.

The vaccines became a source of contention among Republican presidential candidates after some criticized Texas governor Rick Perry for trying to mandate that all girls in his state be vaccinated. Representative Michele Bachmann falsely suggested in televised remarks that the vaccine causes mental retardation.

But many men, including Bruce Arbaugh, 56, of Reynoldsburg, Ohio, believe in vaccination. Two years ago Arbaugh noticed a painless bump on his neck that he thought was from a bee sting. After two weeks it had almost disappeared from view until a bike ride gave him a stiff neck. When his wife, Diane, rubbed his neck, she felt a lump the size of a golf ball. Arbaugh went to see a nurse who, thinking he had an infection, prescribed two different courses of antibiotics over two weeks to no effect. X-rays and other tests were inconclusive until a second biopsy finally showed cancer. A surgeon removed 30 lymph nodes under Arbaugh's jaw, 12 of which were cancerous. Radiation and drugs eventually rid him of the disease, although he had to have most of his back teeth removed.

To help prevent cases like Arbaugh's, Dr. William Schaffner, chairman of the Department of Preventive Medicine at Vanderbilt University, says vaccinating boys against HPV is imperative because it prevents "a notable number of cancers," many of which are diagnosed too late and require ineffective and often disfiguring treatment. "Is it worth it to prevent those cancers?" he asks rhetorically. "Oh, God, yes."

See also: How to Minimize HPV and Cancer Risk