Merck's human papillomavirus vaccine Gardasil is effective in preventing vaginal and vulvar tumors, according to a study to be published on Saturday in the journal Lancet, Dow Jones reports.
Gardasil in clinical trials has been shown to be 100% effective in preventing infection with strains 16 and 18, which together cause about 70% of cervical cancer cases, and about 99% effective in preventing HPV strains 6 and 11, which together with HPV strains 16 and 18 cause about 90% of genital wart cases, among women not already infected with these strains.
FDA in June 2006 approved Gardasil for sale and marketing to girls and women ages nine to 26, and CDC's Advisory Committee on Immunization Practices later that month voted unanimously to recommend that girls ages 11 and 12 receive the vaccine, which is given in a three-shot series. Merck last month announced that it has submitted an application to FDA for extended approval of Gardasil to help prevent vaginal and vulvar cancers.
After three years of follow-up, the study found that the vaccine was 71% effective in preventing vaginal and vulvar cancers related to HPV strains 16 and 18 among women who previously had been exposed to HPV strains 6, 11, 16 and 18.
It was 100% effective among women who previously had not been exposed to those strains. The vaccine was not effective in fighting vaginal or vulvar lesions that had already formed, according to the study.
According to Merck, vaginal and vulvar cancers account for about 3% and 4% of gynecological cancers, respectively. According to HealthDay News/Forbes, HPV is present in about 80% of the 6,000 vaginal and vulvar cancers diagnosed annually in the U.S.
Source: Kaiser Family Foundation