Ask Dr. K: Undetected truth about HPV

There are about 200 different strains of HPV. Some strains cause warts; other strains cause cancer of the cervix, anus, penis and throat (including the base of the tongue and tonsils). Sexual contact, including oral sex and deep kissing, can transmit HPV from one person to another. Many men who have sex with other men are infected with HPV.

Fortunately, most people sexually exposed to HPV never develop symptoms or health problems. That’s true even of the strains of HPV known to cause cancer. Most HPV infections go away by themselves. But in some people, the infection can persist and cause long-term problems, including cancer.

There are ways to prevent HPV-related oral cancer, depending on your age. Pre-teens, teens and young adults of both sexes can get vaccinated against HPV. The Centers for Disease Control (CDC) recommends that both young women and young men be vaccinated with the HPV vaccine. The two available HPV vaccines provide excellent protection against sexually transmitted HPV. Avoiding oral sex will also protect against oral cancer, although not all cases of oral cancer are caused by this virus.

These two vaccines were approved in 2006 and 2009. They have been available just a few years, and only about a third of the kids and young adults for whom the vaccines are recommended have received the vaccine. Nevertheless, a recent study by the CDC found that the number of young people infected with HPV has dropped considerably. Prior studies have shown that the vaccines given to girls and young women also reduce the risk of cancer of the cervix later in life.

Vaccination won’t help people beyond their mid-20s or the millions of people already infected with HPV. Using condoms can prevent the spread of the virus during penile-vaginal, penile-anal or penile-oral sex. Using a dental dam (a thin piece of latex) can help prevent the spread of the virus during oral-vaginal sex.

If you’ve been infected with the virus, diagnosing an HPV-related oral cancer as early as possible greatly improves the chance of cure. See your doctor if you have any of these symptoms for more than two to three weeks:

— A sore in your mouth or on your tongue that doesn’t heal.

— Persistent pain with swallowing or sore throat.

— A lump in your neck that persists.

The discovery that HPV was the major cause of cancer of the cervix led to diagnostic tests for the virus, as well as to the HPV vaccines. These discoveries and inventions have been honored with the Nobel Prize and have saved hundreds of thousands of lives. It was government-supported research that made the discoveries possible.

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.