DEAR DOCTOR K: My 14-year-old daughter got the Gardasil vaccine, which protects her from cervical cancer caused by HPV. But boys can get HPV, too. Should my teenage son also get the vaccine?
DEAR READER: HPV stands for human papilloma virus. There are more than 100 strains of HPV; about 40 of these strains can be transmitted by sexual contact. So-called low-risk strains cause genital warts. High-risk strains can cause cancers of the cervix, anus, penis and throat. I’ll call these the HPV-related cancers. Not all of these cancers are caused only by HPV, but the virus is an important cause of each.
Most cases of cervical cancer in women in the United States are caused by HPV. HPV can also cause cancer in men, including invasive cancer of the penis and anus. But these cancers are uncommon, and not all cases are caused by HPV. Some strains of HPV have also been linked to cancer of the mouth and throat.
HPV is very common. Most sexually active adults become infected with HPV before the age of 50 — and most of them don’t know they have it. It doesn’t cause symptoms, but infected adults can still transmit HPV to their sexual partners. Safe sexual practices such as using condoms can reduce the risk of infection, but since condoms don’t cover all potentially infected tissues, protection is incomplete.
Fortunately, many people with HPV infection never develop cancer from it. However, people with HPV infections — including “silent” infections that cause no symptoms — are at much higher risk for getting HPV-related cancers.
To sum up: A person can have an HPV infection and not know it. He or she can pass the infection to a sexual partner, and the partner may not know it (because they, too, may not have symptoms). And both people are at increased risk for HPV-related cancers.
That’s why it is recommended that both girls and boys be vaccinated against the virus in the years before they become sexually active. The vaccination greatly reduces the risk that they will become infected and suffer the possible consequences of that infection.
The Gardasil vaccine (also known as HPV4) was approved for boys in the United States in 2009. The vaccine protects against two low-risk strains of HPV and two high-risk strains. These four strains of HPV are responsible for most cases of genital warts and HPV-related cancers.
Current guidelines recommend that boys aged 11 or 12 years be vaccinated with Gardasil. The vaccine is given as a series of three doses. The first dose can be given as early as age 9. Males aged 13 to 21 who have not had the vaccine or didn’t get all three doses should also be vaccinated. All men can get the vaccine through age 26.
Even with a vaccine, men and women should also remember to prevent HPV the old-fashioned way: by practicing safe sex.
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.