By Heather Boerner
The human papillomavirus (HPV) garnered news headlines again this week when researchers from Moffitt Cancer Center in Tampa, Fla., revealed that 50 percent of U.S. men are infected with HPV at any given time. In February 2010, Ohio State University researchers said that HPV causes more than 60 percent of oropharynx cancers (a type of throat cancer), making the virus a bigger risk factor for that kind of throat cancer than tobacco. No wonder HPV is a hotbed of medical research right now: It's extremely common, partly vaccine-preventable, and plays a significant role in multiple kinds of cancer, including cervical cancer.
But for all the buzz about HPV in the scientific community, experts worry that many people are still fuzzy on details about the virus - including how it's transmitted, who's most at risk, and how to protect yourself from infection. "There's so much people don't know or misunderstand about HPV," says William Robinson, MD, a professor of gynecologic oncology at Tulane University in New Orleans. Everyday Health asked him and other leading experts to shed light on the most common HPV knowledge gaps.
1. Odds are you've probably had HPV. It's the most common sexually transmitted infection in the country: 20 million people are currently infected and 6 million more will be diagnosed this year. "If you've been sexually active, you've got at least a 50 percent chance of having had the virus," says Dr. Robinson. Some data suggests that more than 80 percent of sexually active women will get HPV at some point.
HPV is actually an umbrella term for more than 100 strains of viruses, most of which are relatively harmless. About 40 of these can be transmitted sexually, and a yet smaller fraction can cause cancer or genital warts.
Most of the time, you'll never even know you've had HPV, because most strains (except those that cause warts) are symptomless. And in 90 percent of cases, the immune system clears the virus naturally within two years, according to the U.S. Centers for Disease Control and Prevention (CDC).Related: Who's Most at Risk for HPV?
2. Even abstinence can't completely protect you from HPV. While condoms can reduce your risk of HPV infection, they can't eliminate it entirely. "The virus can live in the scrotum and the hair-baring areas of the genital tract," says Barbara Goff, MD, director of gynecological oncology at the University of Washington, so any foreplay that involves skin-to-skin genital contact can transmit the virus. So can oral and anal sex. "That's why it's so important for young people to get vaccinated for HPV, well before they become sexually active," says Goff.
Related: The HPV and Oral Sex Link
3. If you're infected, your current partner may not be to blame. If you learn you have HPV (this is most likely to occur after an abnormal Pap test result; most doctors don't routinely test for HPV otherwise), don't jump to conclusions about where you contracted the virus. "Some patients assume that their current sexual partner gave it to them," says Robinson. "But that's probably not the case. The women who develop cervical cancer at age 40 probably got infected shortly after [having sex] with their first sexual partner." That's because HPV can remain dormant for years before it starts causing damage to cells that can lead to cancer. HPV-triggered cancers can take years, or even decades, to develop.
4. If you've had abnormal Pap smears, you may be at increased risk for other cancers caused by HPV. Most people who know about HPV associate it with cervical cancer, but the virus is increasingly implicated in other forms of cancer, including head and neck cancers and those of the lower genital tract, including the vulva, vagina, anus, and penis. Evidence suggests that if you've had cervical cancer or precancerous changes in the cervix (known as dysplasia), you're also at a greater risk of cancer in these other areas, says Goff.
But before you panic, know that these cancers are still rare. The CDC estimates that each year in the United States about 2,700 women and 1,700 men get anal cancer; 1,000 men get penile cancer; 3,700 women get vulvar cancer; and 1,000 women get vaginal cancer, compared to 12,000 cases of cervical cancer.
Unfortunately, there are no approved screening tests for these cancers, although the use of an anal Pap test to detect anal cancer is a hot-button issue in the medical community now. There are currently no national screening guidelines for anal cancer, and the test is not routinely offered to heterosexual women and men, but talk to your doctor about getting one if you're concerned about your anal cancer risk.
5. Smoking raises your risk of HPV-related cancer. "Smoking weakens the immune system, which can allow HPV to grow more rampantly," says Sharyn Lewin, MD, an assistant clinical professor of gynecologic oncology at New York Presbyterian Hospital-Columbia University Medical Center. If you want to prevent a nascent HPV infection from turning into a precancerous or cancerous growth, kick your cigarette habit.
6. The HPV vaccine isn't just for girls. As the Moffitt study found, half of men have the HPV virus. The vaccine will not only reduce rates of cervical cancer in women, it also has direct health benefits for men. The vaccine can prevent 90 percent of genital warts in men, a recent New England Journal of Medicine paper found. (The FDA approved the vaccine for boys ages 9-21 in 2009 for this purpose). And though studies have yet to be done, many researchers believe that vaccinating boys will eventually reduce rates of head and neck and other cancers as well.Related: Can Circumcision Prevent HPV Spread?
7. You still need Pap smears even if you've gotten the HPV vaccine. A message for your daughter: The vaccines Gardasil and Cervarix only protect against two cancer-causing HPV strains. Also, research shows that only 30 percent of girls who get the first shot (it's delivered in a three-part series) come back to get the other two; not being fully vaccinated can actually reduce your immunity. In addition, she could have already been exposed to a risky HPV strain before getting vaccinated against it.
8. The vaccine doesn't treat HPV. This may seem obvious, but it bears repeating: The HPV vaccine is only preventive - it doesn't fight the virus in people who've already contracted it. That's partly why it's approved only for people in their twenties and younger; chances are that older populations have already been exposed to the two cancer-causing strains the vaccine protects against.
There's no treatment for the HPV virus; if you've been infected, it has to clear on its own. Women who have cervical dysplasia detected after an abnormal Pap smear can have procedures to remove the damaged cells.
Related: 8 Ways to Prevent HPV
Learn more in the Everyday Health Sexual Health Center.