About 50% of men from a sample of the general public are infected with the human papillomavirus, according to a study published online in the medical journal The Lancet. Per year, 6% of men will acquire a new HPV 16 infection, the virus most well known for causing cervical cancer in women and also causing cancers in men. Furthermore, having multiple partners makes a man more likely to have an HPV infection.
In the United States an estimated 32,000 cases of cancers in men and women in 2009 were attributable to HPV infection. These were cancers of the cervix, vagina, vulva, penis, oral cavity, head and neck, and anal canal. Anogenital warts are the most common outcome of HPV, with 205 cases per 100,000 diagnosed every year in the United States. Because the virus is transmitted so easily during sex, understanding the nature of HPV is of crucial public health importance and can be used in modeling to establish whether vaccinating men would be cost-effective.
The study analysed 1,159 men ages 18 to 70 years (mean 32 years) from the U.S., Brazil, and Mexico, all of whom were HIV-negative and had no history of cancer. They were assessed every six months for an average of more than two years. The incidence of a new genital HPV infection with any HPV type was 38.4 per 1,000 person months. The chances of cancer-causing (oncogenic) HPV infection was 2.6 times higher for men who had at least three male anal sex partners compared with no recent partners. The median duration of HPV infection was 7.5 months for any HPV and 12 months for the cancer-causing HPV type 16. The authors say, “We noted no association with age and incidence of any, oncogenic, or nononcogenic HPV types, although the probability of clearing these infections increased with age.”
They conclude, “The incidence of genital HPV infection in men was high and relatively constant across age groups in Brazil, Mexico, and the USA. The results from this study provide much needed data about the incidence and clearance of HPV infection in men; these data are essential for the development of realistic cost-effectiveness models for male HPV vaccination internationally.”