Human Papillomavirus (HPV)

The human papillomavirus (HPV) is thename for a group of related viruses, about 30 percent of which are sexually transmitted. The infection is very common. According to the American Social Health Association, about 75 percent of Americans 15 to 49 become infected at some point. Currently, about 20 million people in the U.S. are believed to have an active infection. Roughly 5.5 million new cases occur every year.

More than 100 different strains of HPV have been identified. Some are classified as low-risk and others as high-risk. The low-risk strains cause genital warts, small growths around the genitals, anus, cervix or vagina. High-risk strains cause abnormal changes in cervical cells, leading to abnormal Pap smears and increased risk for cervical cancer. About 70 percent of cervical cancers in the U.S. are linked to HPV 16 or 18.

HPV in Men

HPV infection can occur in men and women. In fact, a recent study found that more than half of 290 men developed an HPV infection during the study period (about 15.5 months). The most common strain was HPV 16, the one associated with cervical cancer in women. Researchers are finding that men with HPV are also at higher risk for cancer, namely head and neck cancers and cancer of the penis or anus. In fact, the CDC estimates HPV accounts for 7,600 cancers in men annually.

The HPV Vaccine for Men

In 2006, the FDA approved a vaccine to protect against four risk strains of HPV – HPV 16 and 18 (associated with 70 percent of cervical cancers) and HPV 6 and 11, accounting for 90 percent of genital warts). The vaccine is called Gardasil®. It’s recommended for females 11 to 26 and is given in three doses over six months.

Even though HPV infects women and men, Gardasil is currently only approved for women. Researchers have been testing the vaccine in men aged 16 to 26. Half of the men received the vaccine and half received a placebo. Follow-up tests are being done every six months to check for physical signs of genital warts or evidence of infection in the blood.

The study is still ongoing, but preliminary results have been obtained. Researchers say, so far, the vaccine has shown to reduce the risk for genital warts and precancerous lesions in men by 90 percent.

Anna Giuliano, Ph.D., Cancer Epidemiologist with H. Lee Moffitt Cancer Center and Research Institute in Tampa, FL, is the lead researcher for the study. She says vaccinating males against HPV may reduce the incidence of some head and neck cancers, anal cancer and penile cancer. Vaccination also closes the loop on transmission, preventing some non-vaccinated women from potential infection as well. Merck has recently submitted the study data to the FDA for consideration of approving Gardasil for men. The manufacturer hopes to have the approval late this year.

For information on HPV or the vaccine: American Cancer SocietyAmerican Social Health AssociationCenters for Disease Control and Prevention