May 13, 2009

Gardasil Blocks About Half of Cervical Lesions

The human papilloma virus (HPV) vaccine Gardasil reduced the number of abnormal cervical Pap test results by 17 to 45 percent, depending on the abnormality, according to a study presented at the International Papillomavirus Conference in Malmö, Sweden. The vaccine also reduced the need for invasive diagnostic and treatment produces in women ages 16 to 26 compared with those who received a placebo.

Gardasil is an HPV vaccine that is designed to protect against infection and disease progression with two cancer-causing HPV strains—16 and 18—and two other strains—6 and 11—associated with genital warts. Other HPV strains can lead to cervical cancer, however, and though researchers hope that Gardasil will reduce the overall incidence of cervical cancer, this has not yet been proved.

To examine Gardasil’s cancer fighting potential, Jorma Paavonen, MD, from the University of Helsinki in Finland, and his colleagues from the Quadrivalent HPV Vaccine Phase III Study compared the vaccine to a placebo in over 9,000 women. Paavonen’s team looked not only at the development of low- and high-grade cervical lesions from any of 14 stains of HPV, but also at the need for certain diagnostic tests and treatment of the lesions. The average follow-up time was three and a half years following the last of three vaccine injections.

The authors found that Gardasil reduced the number of low-grade lesions—those least likely to cause cancer—by 17 percent. For high-grade lesions—those more likely to cause cancer—Gardasil bested the placebo by 45 percent. These also corresponded with a 42 percent drop in the need for cervical lesion treatment in those receiving Gardasil compared with the placebo.

While the authors comment that Gardasil was significantly superior to a placebo in reducing the development of cervical lesions, it is too early to tell how much the vaccine will guard against cervical cancer.

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