HPV Vaccine May Also Prevent Vulval And Vaginal Cancer

An international study showed that Gardasil, a vaccine that protects against infection by some types of the human papillomavirus (HPV), was 100% effective in preventing vaginal and vulvular neoplasia or pre-cancerous lesions in women who were not already infected with the virus.

The study, conducted by a large international team of researchers from the United States, Mexico, Canada, New Zealand, Austria, Finland, Colombia, and China, was published in the May 19, 2007, issue of the journal The Lancet.

Gardasil (quadrivalent HPV types 6, 11, 16, 18 recombinant vaccine) is a vaccine developed by Merck and Co. (Whitehouse Station, NJ, USA), and is designed to prevent infection with HPV types 6, 11, 16, and 18 in uninfected young women. HPV types 16 and 18 are believed to cause 70% of cervical cancers, the second most common cause of death from cancer among women worldwide. HPV types 6 and 11 also cause a high degree of genital wart cases. Moreover, HPV 16 has been implicated in some throat cancers.

In this study, researchers looked at how well Gardasil prevented lesions that can lead to cancers of the vulva and vagina. Among younger women, vulval and vaginal cancers are frequently related to infection with and are preceded by high-grade lesions called vulval intraepithelial neoplasia (VIN2-3) and vaginal intraepithelial neoplasia (VaIN2-3).

Not all lesions develop into cancer, since they can be benign as well as malignant, but high-grade lesions are indicators for possible development of cancer in that if a tumor is going to develop, they appear first.

In this new study, researchers did a combined analysis of three randomized clinical trials to evaluate how effectively Gardasil prevented these lesions; 18,174 women aged between 16 and 26 years were randomly assigned to receive either the vaccine or a placebo. The dose, given by injection, was administered at the start of the trial and then at months 2 and 6. The women had detailed medical exams of the anal and genital area at the beginning, one month after the last dose, and at 6- to 12-month intervals thereafter for up to four years.

Any lesions found and thought to be suspicious were sent for biopsy and an analysis was performed by a panel of pathologists who did DNA tests to find out if HPV was present and if it was of the type in the vaccine. Specifically, the researchers were interested in matches between VIN2-3 or VaIN2-3 lesions and HPV16 or HPV18.

The study's results demonstrated that: the vaccine was 100% effective against VIN2-3 or VaIN2-3 associated with HPV16 or HPV18 among women not already infected up to one month after the last dose. Overall, in the intention to treat population, which included all 18,714 participants, some of whom could have been infected, the vaccine was 71% effective against VIN2-3 or VaIN2-3 associated with HPV16 or HPV18. The vaccine was 49% effective against all VIN2-3 or VaIN2-3, "irrespective of whether or not HPV DNA was detected in the lesion.” The most common adverse side effect was pain at the site of the injection.

The researchers concluded that, "prophylactic administration of quadrivalent HPV vaccine was effective in preventing high-grade vulval and vaginal lesions associated with HPV16 or HPV18 infection in women who were naive to these types before vaccination. With time, such vaccination could result in reduced rates of HPV-related vulval and vaginal cancers.”

Gardasil was approved by the U.S. Food and Drug Administration (FDA) in June 2006 and is recommended by the US Centers for Disease Control and Prevention (CDC) for use in girls and women aged 11 to 26.

Gardasil has been approved for use in more than 70 countries, in some of which it is marketed as Silgard. These nations included the United States, the 27 countries of the European Union, Australia, Brazil, Canada, Mexico, New Zealand, and Taiwan. In a separate collaboration, India's Council of Medical Research and Merck are studying Gardasil in India.


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