Preliminary research by UA scientists suggests that a virus linked to cervical cancer in women also may pose a cancer threat to heterosexual men.
While the effects of the human papillomavirus — HPV — in women have been well-documented, results from an Arizona Cancer Center study released on Monday show that sexually active heterosexual men could be making themselves vulnerable to an even greater cancer risk than had been previously thought.
One of the most common sexually transmitted diseases, HPV has been shown to cause genital warts among both sexes and has seen increasing attention in recent years because it can lead to cervical cancer in women.
The virus also has been linked to anal cancer in homosexual men.
What's been less known is what long-term impact the virus has on heterosexual men and whether it could lead to anal cancer, said Alan Nyitray, the University of Arizona's lead analyst for the study.
According to the Centers for Disease Control and Prevention, the cancer risk to heterosexual men posed by HPV is low. Homosexual and bisexual men are 17 times more likely to develop anal cancer as a result of HPV than heterosexual men are, according to the CDC's Web site.
But the UA's research appears to contradict those figures.
Conducted with the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Fla., the UA study collected biological specimens from 253 men in Tucson and Florida who said they'd had sex with a woman in the last year.
Of the 222 men in the survey who said they'd had sex only with women in their lives, roughly 25 percent had an anal HPV infection, according to the research.
Of that group, one-third had a strain of HPV that could lead to anal cancer, a rare form of cancer unrelated to colon cancer, the study found.
While the study's results will need to be confirmed in a larger population, the findings show that heterosexual men should be worried about contracting HPV, said Nyitray, a research scientist at the UA's Mel and Enid Zuckerman College of Public Health.
"We've primarily been talking about HPV in the context of cervical cancer, so I think it's understandable that men have been less concerned about it," he said. "But men play a role in transmitting the virus, so they should be concerned."
The cancer center already has acquired a two-year, $171,000 grant to study the presence of HPV among 1,200 heterosexual men from the United States, Mexico and Brazil, but more research needs to be conducted to determine how long the infection lasts among straight men.
In most instances, men and women of all sexual preferences who contract HPV usually beat the virus on their own without showing any symptoms. But if the infection persists, it can lead to cervical cancer among women and anal and penile cancer among men, according to the CDC.
It's not clear whether the heterosexual men in the study who contracted HPV had a temporary strain of the virus or if it was persistent, Nyitray said.
Answering that question could help determine whether an HPV vaccine for heterosexual men similar to one currently on the market for women would be needed.
"Maybe it's just a transitory virus that doesn't pose a risk," Nyitray said. "From that perspective, a vaccine wouldn't be seen as that helpful."
The HPV vaccine for women, known as Gardasil, has been controversial since it was introduced in 2006.
The vaccine has been endorsed by researchers and doctors who cite its ability to prevent cervical cancer and genital warts, and many hoped that it would become mandatory for teenage girls.
But watchdog organizations, conservative Christian groups and others have resisted mandatory vaccination, citing potential health risks and what they see as tacit approval of premarital sex.
The vaccine protects against HPV strains that lead to 70 percent of cervical cancer in women and cause 90 percent of genital wart cases.
More than 10,000 women in the United States contract cervical cancer each year, and about 3,800 die, according to the CDC.