HPV: Men can get it too
With human papillomavirus, girls and women have been getting all the attention.
Parents across the nation have rushed to have their daughters vaccinated against the virus. States are wrestling with whether to require that adolescents get the vaccine. And recent research found that many more girls and women are infected with human papillomavirus than was previously thought -- more than one-quarter of females ages 14 to 59.
Now the attention is turning to boys and men.
As many as 60% of men ages 18 to 70 are infected with HPV, according to data not yet published, raising the question of whether the new vaccine will be effective in reducing diseases linked to the virus unless men, not just women, are immunized.
Several studies are underway to better understand the virus in males and whether the new HPV vaccine, Gardasil, also will work for them. As researchers already know and as the new data confirms, HPV is not just a women’s issue.
“With any transmittable disease, you want to understand the entire cycle of how things spread,” says Thomas Broker, an HPV expert and professor of biochemical and molecular genetics at the University of Alabama, Birmingham. “With HPV, men are clearly part of that equation.”
Human papillomavirus is best known for causing cervical cancer, with about 9,700 cases diagnosed in women in the U.S. each year.
Gardasil, a three-shot regimen, was approved last year for girls and women ages 9 to 26. It protects against four strains of the HPV virus that are most likely to cause cervical cancer and genital warts in women.
But much less is known about the consequences of HPV infection in men.
“We know they transmit it to women, but what is the rate of transmission?” says Anna Giuliano, a researcher at the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Fla., who is leading three government-funded studies on HPV infection in men. She is also a paid speaker for Merck, the maker of Gardasil.
Several studies are attempting to address this question, as well as ones about what strains of HPV are most common in men. New data show that HPV infection is quite common in men of all ages, while the highest rates of infection in women tend to occur in the early 20s before declining and then spiking again in women in their 40s and 50s.
“We’re seeing a really high prevalence in men, and we see little change in prevalence across the age span,” says Giuliano, who found the 60% prevalence rate in one of her studies. That data will be published later this spring in the journal Cancer Epidemiology Biomarkers & Prevention. “We need to know if women in their 40s and 50s are acquiring new infections from their partners.”
HPV infection isn’t inconsequential in men. Certain strains of the virus are known to cause genital warts in men as well as women.
And those infections are estimated to be the cause of about half of all anal, penile, vulvar and vaginal cancers and about 20% of the cause of all oral cancers, says Dr. Dean Blumberg, an associate professor of pediatric infectious disease at UC Davis. Blumberg is a member of Merck’s speakers bureau but does not get paid directly by Merck for his services. A speaker’s bureau is a roster of experts who provide educational lectures on particular topics.
About 28,000 Americans are diagnosed with oral cancers each year, and about 4,650 are diagnosed with anal cancer. Penile cancer affects about 1,500 men each year. Although the overall risk of those diseases is low, anal cancer in gay and bisexual men has been rising in recent years.
Worldwide, the consequences of HPV infection in both men and women are even more severe than in the United States, notes Broker, president of the nonprofit International Papillomavirus Society.
More women in developing countries die of cervical cancer than in the United States, he says. Moreover, “we need to know how much real disease men are getting. If you look worldwide, there are about 100,000 new cases of penile cancer each year.”
HPV-related cancer is also more common in people who have compromised immune systems, such as men who are HIV positive.
“This virus can cause cancers in a lot of different places,” says Blumberg. “But in terms of numbers, it doesn’t compare to the number of cervical cancer cases.”
But even if reducing rates of cervical cancer was the singular goal of HPV vaccination, some experts suggest that herd immunity -- vaccinating everybody to reduce circulation of the virus in the population -- will turn out to be the most successful approach.
“If you decrease HPV infection in men, then there will be decreased transmission to women also,” Blumberg says.
Merck is conducting studies of the vaccine’s ability to prevent infection in boys and men. Data on those trials may become available later this year, and the company hopes to apply to market Gardasil to boys and men some time next year.
Studies of Gardasil show that the vaccine provokes an even stronger immune response in boys than in girls, which implies that the vaccine will also prevent HPV infections, Blumberg says. But they have yet to show that boys are protected from HPV infection at satisfactory rates. Researchers are also examining whether the vaccine reduces cases of anal cancer in gay men.
There is “no guarantee” an HPV vaccine will work in men, Broker says, because the skin cells infected by the virus differ greatly in men and women.
Some people aren’t waiting for the results of those studies. High-risk men, such as gay and bisexual men, are reportedly requesting and receiving Gardasil vaccination from their physicians, Blumberg says.
Moreover, he says, “I’ve had nurses tell me they made sure their 15-year-old son was vaccinated because they wanted to decrease the chance of their future daughter-in-law having cervical cancer. They felt strongly about it.”
Historically, vaccination programs have had the most impact when they are gender-neutral.
For example, when the rubella vaccine was introduced in the late 1960s, it was recommended initially for women of child-bearing age because -- while anyone can become infected -- rubella in pregnant women causes serious birth defects.
However, the campaign was only partially effective and eradication of the disease was only achieved after the vaccine was recommended to both boys and girls.
GlaxoSmithKline plans to seek Food and Drug Administration approval next month for its HPV vaccine for girls and women, Cervarix.
And legislation requiring California girls to complete HPV vaccination before entering seventh grade was introduced last week by Assemblyman Edward Hernandez (D-West Covina). Another bill was proposed that would require health insurers to cover the cost of the vaccinations.
Lawmakers in as many as 20 other states have introduced similar proposals. But mandatory vaccination of school-age girls has generated controversy because some parents believe their daughters will not be exposed to the virus or that having the vaccination might encourage sexual activity.
Others object to mandating vaccination for something that is not easily transmitted (unlike chickenpox or measles) and because the shots are costly, about $360 for the series.
“Some people resent the fact that a mandate is targeting just one gender,” says Blumberg. “It does give the appearance of being unfair. We don’t have any other vaccine mandates that are gender specific.”