According to results presented at the 2006 annual meeting of the American Society of Clinical Oncology, Gardasil®-a recently approved vaccine intended to prevent cervical cancer, precancerous genital changes, and genital warts caused by specific types of human papillomavirus (HPV)-reduces the risk of high-grade precancerous changes to the vulva and vagina.
Human papillomaviruses consist of a group of more than 100 different viruses. Gardasil prevents infection with four of these types-6, 11, 16, and 18. HPV types 16 and 18 cause roughly 70% of all cases of cervical cancer, and HPV types 6 and 11 account for roughly 90% of genital warts. Gardasil was approved in June 2006 for use in females between the ages of nine and 26 years.
The types of HPV that cause cervical cancer or genital warts are transmitted sexually. HPV infection is extremely common and generally occurs soon after an individual becomes sexually active. Although most infections resolve on their own, some persist and can lead to precancerous or cancerous changes to the cervix, vulva, vagina, penis, and anus.
Previous reports of the safety and efficacy of Gardasil have focused on the prevention of precancerous changes to the cervix. The results presented at the 2006 ASCO meeting focused on prevention of precancerous changes to the vulva and vagina.
The analysis combined information from three randomized clinical trials conducted in the U.S., Europe, South America, and Asia. The trials enrolled a total of 18,150 women between the ages of 16 and 26. Study participants were randomly assigned to receive three doses of Gardasil or a placebo. Participants were followed for an average of two years.
- There were no cases of HPV16- or HPV18-related vaginal or vulvar precancers among women who received Gardasil.
- Among women who received a placebo, there were 24 cases of HPV16- or HPV18-related vaginal or vulvar precancers.
The researchers concluded that Gardasil is highly effective in protecting against HPV16- and HPV18-related vaginal and vulvar precancers. The vaccine is expected to reduce the occurrence of vulvar and vaginal cancer in addition to reducing the occurrence of cervical cancer.
Reference: Paavonen J, for the FUTURE II Study Group. Efficacy of a Quadrivalent HPV (Types 6/11/16/18) Virus-like Particle (VLP) Against Vaginal and Vulvar Pre-Cancerous Lesions: A Combined Analysis. Presented at the 2006 ASCO Annual Meeting. Abstract #5011.