Fewer Vulvar HPV Infections After HPV16/18 Vaccine

By Will Boggs MD

July 22, 2014

NEW YORK (Reuters Health) - Women who receive the bivalent HPV16/18 vaccine have lower rates of vulvar human papillomavirus (HPV) infection, according to results from the Costa Rica Vaccine Trial.

"It is well established that the bivalent HPV vaccine Cervarix protects against HPV16/18 infections at the cervix," Dr. Krystle A. Lang Kuhs from the National Cancer Institute in Bethesda, Maryland told Reuters Health by email. "Newer studies have demonstrated protection at other anatomic sites of the body where HPV causes cancer, including the anus and the oral region. In this report, we observed protection against HPV16/18 infections at the vulva, which in turn could reduce incidence of vulvar cancer in vaccinated populations."

"While vulvar cancer is extremely rare, approximately 40% of vulvar cancers worldwide are due to HPV16/18 infections," Dr. Kuhs said.

HPV vaccine efficacy against HPV16/18 infections at the vulva hasn't been reported until now, the authors say.

During the final year of the Costa Rica Vaccine Trial, Dr. Kuhs and colleagues collected vulvar specimens from 508 HPV vaccinated women and 536 controls.

Vaccine efficacy at the vulva was 54.1%, compared with 45.8% at the cervix, they reported online June 23rd in The Journal of Infectious Diseases.

In the control arm, the overall prevalence of any HPV type at the vulva was 29.5% (16.8% for carcinogenic HPV types and 17.2% for noncarcinogenic HPV types). The most common carcinogenic HPV types were HPV52 (3.4%), HPV56 (3.4%), and HPV16 (3.0%).

The overall prevalence of any HPV type at the cervix (34.1%) was similar to that at the vulva (22.2% carcinogenic, 17.7% carcinogenic HPV types).

The risk of vulvar HPV infection in the control group was significantly associated with older age, single marital status, and multiple sexual partners. Risk factors were similar for cervical HPV infection.

During four years of follow-up, women who received the bivalent HPV vaccine were less likely to develop HPV16/18 infections compared to unvaccinated women, and "protection was similar to the level of protection observed for cervical HPV16/18 infections," Dr. Kuhs said.

"The vaccine is most effective prior to exposure to the virus," she added. "Therefore, clinicians should continue to encourage HPV vaccination for boys and girls before initiation of sexual activity, particularly in the recommended age range of 11 to 12 years."

Dr. Julia Brotherton, Medical Director of the National HPV Vaccination Program Register in East Melbourne, Victoria, Australia, agreed. She told Reuters Health by email, "HPV vaccines provide effective protection against the two HPV virus types which are the main causes of genital cancers. Vaccinating your daughter or son in early adolescence is the best way to provide her or him with protection against these cancer causing viruses."

Dr. Xavier Bosch from Chicago Institut Català d'Oncologia, Barcelona, Spain has published widely on HPV infections and vaccines. He told Reuters Health, also by email, that the findings also encourage male vaccination, since men are "currently experiencing a significant increase in their oropharyngeal cancer incidence rates."

Dr. Colleen K. Stockdale from University of Texas, San Antonio, Texas told Reuters Health by email that while the HPV16/18 vaccines are protective against high-risk HPV when given before infection, "not all high-risk HPV types can be prevented," and therefore, "routine cervical cancer screening as well as periodic evaluation to exclude lesions should be undertaken."

The study results will also be reported in an oral presentation at the 29th International Papillomavirus Conference, 20-25 August 2014, in Seattle, Washington.

SOURCE: http://bit.ly/1p7DCAT

J Infect Dis 2014.

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