Recent data published in Clinical Infectious Diseases suggest that anal HPV infections among women are common but typically clear within 3 years.
However, persistence of anal HPV infections is associated with sexual behaviors, including anal intercourse and anal finger sex, and may suggest that the anus is being reinfected, according to Anna-Barbara Moscicki, MD, of the division of adolescent medicine at the University of California, San Francisco.
“It may be that, eventually, the immune system is overwhelmed and the infection is not cleared,” Moscicki told Infectious Disease News. “Persistence is important since it is necessary for anal cancer to occur. In the United States, anal cancer is more common in women than in men, and this is likely due to anal sex behaviors.”
Moscicki and colleagues evaluated a group of 75 women who tested positive for anal HPV and had 3 or more years of anal HPV testing while enrolled in an HPV cohort study. The women were followed for a mean of 84.5 years. The researchers estimated time to clearance of the infections and risk for persistence of infection.
By year 3, 82.5% of non-HPV16 high-risk HPV infections had cleared, as had 82.6% of low-risk HPV and 76.2% of HPV16 infections. HPV16 infections cleared slower than three other high-risk HPV types, including HPV56, HPV66 and HPV39. The other high-risk types, 18, 51, 52, 53 and 59, cleared at similar rates to HPV16. Only 36.4% of women were negative for all HPV types.
The multivariate analysis showed that concurrent cervical HPV16, weekly alcohol use, anal touching during sex, recent anal sex and no condom use during sex were associated with HPV16 persistence. A higher number of new sex partners and condom use during vaginal sex were associated with clearance.
“It may be of importance to counsel women with cervical neoplasia that they are at risk for anal cancers,” Moscicki said. “Avoiding anal intercourse or always using condoms during anal sex in these women may be important but further studies are needed.”
Moscicki said other research questions remain, including what immune mechanisms are important in anal HPV clearance and the role of partner vs. self-inoculation in anal HPV persistence. – by Emily Shafer
Anna-Barbara Moscicki, MD, can be reached at firstname.lastname@example.org.
Disclosure: Moscicki has served as an advisory board member to Merck.