HPV and cancer: The lesser-known risks

When someone mentions the human papillomavirus (HPV), you probably think of two things: cervical cancer and vaccinations for young girls and boys.

But several other types of cancer can be caused by HPV. Many of them are affecting growing numbers of both women and men.

"Worldwide, cervical cancer is a huge and preventable problem, but people should be aware of other cancers linked to HPV," says Erich Sturgis, M.D., professor in Head and Neck Surgery and Epidemiology at MD Anderson. "And they should know that the HPV vaccine can help protect them from these cancers too."

HPV causes six cancers

Most adults get HPV at some point, but most never know they have the virus. That's because the immune system usually clears the infection before it's detected. However, a small number of HPV cases lead to genital warts or cancer.

Oropharyngeal cancer is the most common HPV-related cancer in men, Sturgis says. It forms in the tonsils, and around the back of the throat and tongue.

This type of cancer is as common in men as cervical cancer is in women. And it's become more common in the past 20 years.

About 75% of oropharyngeal cancers are the result of HPV infections. But unlike cervical cancer, which often can be found with routine Pap tests, there's no way to screen for oropharyngeal cancers.

Other cancers caused by HPV also are on the rise. These include:

• Anal cancer. About 12% to 15% of HPV-related cancers in men and women are in the anus.
• Vulvar cancer, which makes up around 12% of HPV-linked cancers in women.
• Rare genital cancers, including vaginal and penile cancers. These account for a small number of cancers linked to HPV.

Cancer forms long after infection

Exactly how does HPV cause cancer? In simple terms, it contains a little bit of DNA. That viral DNA mixes with your body's cells and disrupts some of their functions. As your cells reproduce, those changes can lead to cancer and the spread of cancer cells.

"Usually cancer is believed to develop after an HPV infection has been present for a long period," Sturgis says. "When cancer is found, your body typically has cleared the HPV infection from your system."

The cancer often doesn't show up until people are in their 40s (cervical cancer) or 50s (oropharyngeal cancer).

"But the HPV infection that triggered the cell changes probably occurred decades earlier," Sturgis says.

Early vaccination is key

That's why vaccination is so important, especially before young men and women become exposed to HPV. Research shows the real key to limiting or avoiding many HPV-related cancers is to vaccinate boys and girls betwee the ages of 11 or 12. That's when their immune systems respond best to the vaccine.

The HPV vaccine can be given as early as age 9 and up to age 45. The vaccine is most effective at age 11-12.

The HPV vaccine can prevent close to 90% of cervical cancers, experts say. It also protects against HPV strains that may lead to genital, anal, and head and neck cancers. And, like the previous vaccines, it's effective only for young adults who haven't been exposed to HPV.

"If we can get 100% of 11-year-olds vaccinated, we can basically wipe out HPV-related cancers," Sturgis says.

In the end, the message he and other cancer experts have for parents is clear: "Whether you have boys or girls, you must get your kids vaccinated."