HPV Vaccine Protects Against Anal Infection
Human papillomavirus (HPV) is primarily known for its role in causing cervical cancer. Two strains of the virus – strains 16 and 18 – are estimated to be responsible for 70% of cervical cancer cases, leading to about 500,000 new cases and 270,000 deaths worldwide each year.
Both of the HPV vaccines available in the United States have been shown to be effective in preventing cervical infection with strains 16 and 18. The Gardasil quadrivalent vaccine also offers protection against two strains that cause genital warts. But HPV’s role in cancer is not limited to cervical cancer; the virus can also cause oral, anal, and penile cancer.
The results of a recent study indicate that in addition to preventing cervical cancer, HPV vaccines are also effective at preventing HPV infections that can cause anal cancer in women. Like cervical cancer, most anal cancers are caused by HPV, with strains 16 and 18 accounting for up to 80% of cases. In a large study using the Cervarix vaccine that offers protection against strains 16 and 18, Aimée Kreimer, PhD (National Cancer Institute) and colleagues found that the vaccine was 62% effective at preventing HPV infection at the anus. Among participants in the trial who did not have HPV infection at the start of the study, the vaccine was 83.6% effective at preventing anal infection.
HPV vaccines could prove a valuable tool against anal cancer, which is on the rise in the United States. Currently it affects about 1.5 per 100,000 women, and incidence rates are even higher in men.
Other studies are underway to determine whether current HPV vaccines will also be effective in preventing other cancers caused by the virus.
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