By Steven Reinberg
THURSDAY, Jan. 19, 2017 (HealthDay News) -- Many American men are infected with the cancer-causing human papillomavirus (HPV), but unlike women, men are more likely to stay infected throughout their lives, a new study finds.
About 45 percent of U.S. men are infected with the sexually transmitted disease, as are 45 percent of women. Among women, the prevalence of HPV infection drops to about 22 percent as they age, but it remains high among men, said lead researcher Dr. Jasmine Han. She is in the division of gynecologic oncology at Womack Army Medical Center, in Fort Bragg, N.C.
"We don't know why it stays high in men while it drops in women," she said. "Among men it's higher than expected."
Han speculates that the virus may remain in men because it lives in the penile glands, while in women, the virus is near the surface of the vagina and is more easily shed.
Although a vaccine against HPV has been available since 2009, coverage remains low. Only about 11 percent of men and 33 percent of women have been vaccinated, Han said.
HPV is the most common sexually transmitted disease among men and women in the United States, according to background information in the study. About 79 million Americans are infected with some type of HPV, with approximately half of new infections occurring before age 24, the study authors said.
Most people infected with HPV don't know they have it and don't develop health problems from it, according to the U.S. Centers for Disease Control and Prevention.
But HPV is not a benign infection. More than 9,000 cases of HPV-related cancers occur in men each year. HPV is the cause of 63 percent of penile, 91 percent of anal, and 72 percent of oral and throat cancers, the researchers noted.
In addition, HPV among men is an indirect cause of cervical cancer in women. The virus is also responsible for 90 percent of genital warts. HPV can also lead to tumors in the respiratory tract, called respiratory papillomatosis.
Han believes that the HPV vaccine should be mandatory for both boys and girls.
The CDC recommends that all boys and girls aged 11 to 12 get two doses of the HPV vaccine.
"We want our children to be vaccinated with the HPV vaccine because it is a cancer vaccine," Han said. "By getting vaccinated, you can prevent your sons and daughters from getting these HPV-associated cancers in later years," she explained.
Fred Wyand is a spokesman for the American Sexual Health Association/National Cervical Cancer Coalition. "This study underscores that HPV is common in men, and that's true throughout most of their lives," he said.
"We're doing a better job of getting young males vaccinated against HPV, but uptake is still way below the levels we'd like to see," Wyand added.
To get parents to accept the vaccine for their children, Wyand suggested that doctors need to give a "clear, strong recommendation for vaccination and treat HPV immunization as a normal, routine part of adolescent vaccinations."
To gauge the prevalence of HPV infection among men, Han and colleagues used data on nearly 1,900 men who took part in the 2013-2014 U.S. National Health and Nutrition Examination Survey. Samples from penile swabs were tested for HPV.
Overall, a little more than 45 percent of the men were infected with the cancer-causing virus. Among vaccine-eligible men, however, only about 11 percent had been vaccinated.
The lowest prevalence of the virus among men was about 29 percent for those aged 18 to 22, which increased to nearly 47 percent in men aged 23 to 27 and stayed high and constant as men aged, Han said.
It's possible that the lower rate among younger men may have resulted from young men being vaccinated, the researchers said.
The report was published online Jan. 19 in the journal JAMA Oncology.