- The Washington Times - Wednesday, March 2, 2011

Men appear to be at lifelong risk for acquiring human papillomavirus, in contrast to women, who seem to be at less risk for HPV as they age, according to a new study released this week.

Understanding this apparent gender difference is important because HPV is “readily transmitted from men to women, and greatly affects the risk of disease in women,” wrote epidemiologist Anna R. Giuliano and colleagues in their study published online March 1 in The Lancet, the leading British medical journal.

“If indeed men remain at high risk of acquiring new HPV infections throughout their lives, then vaccination of older men might be warranted,” they wrote.

Sexually transmitted HPV most commonly leads to genital warts, but some strains can cause cervical cancer in women, as well as rarer cancers of the vagina, penis, anus, oral cavity, neck and head. In 2009, HPV infections led to an estimated 32,000 cases of cancer.

The new study tracked 1,159 men in cities in Brazil, Mexico and southern Florida for an average of 28 months. The men, aged 18 to 70, provided skin specimens that allowed researchers to detect when they acquired a new HPV infection, what kind it was, and how long it stayed active before being “cleared” by the natural immune system.

The researchers found that half of the men acquired at least one HPV infection during the study, and every year about 6 percent of men acquired a new infection of HPV-16, the strain most associated with development of cancer.

It took the men about seven months to clear themselves of HPV infections in general, but longer — about 12 months — to clear a HPV-16 infection.

As might be expected, men who had multiple sexual partners (50 or more female partners in their lives, or three or more male partners in the prior three months) were at higher risk for acquiring HPV than monogamous or abstinent men.

The new data are expected to assist with cost-benefit assessments for promoting HPV vaccines to men. Since 2006, two vaccines have been developed for females, aged 9 to 26. In 2009, one of those vaccines, Gardasil, was approved for males in the same age range.

HPV infections seem to peak in women during their 20s and then decline. One theory holds that as women age, their immune systems do a better job preventing or clearing infections.

But this immune response doesn’t seem to occur as effectively in men, “and so they remain at risk for acquiring an infection again,” said Ms. Giuliano, who works at the H. Lee Moffitt Cancer Center and Research Institute.

Ms. Giuliano is a consultant to Merck, a HPV vaccine maker, but the study was entirely funded by the National Cancer Institute, a part of the National Institutes of Health.

The new study shows how universal this viral infection is, said Fred Wyand, spokesman for the American Social Health Association, a national nonprofit that focuses on sexual health. “It really points out the ‘human’ in human papillomavirus,” he said.