There are two vaccines, Gardasil (made by Merck) and Cervarix (made by GlaxoSmithKline), approved to prevent cervical cancer caused by HPV (human papillomavirus). Both vaccines protect against HPV strains 16 and 18, which are estimated to account for 70% of cervical and vaginal cancer cases. Gardasil (human papillomavirus [HPV] vaccine, quadrivalent) also offers protection against two strains that cause genital warts.
Gardasil was the first of the two vaccines to be introduced in the United States. In 2006, it was approved for use in preventing cervical cancer and genital warts for girls and women between nine and 26 years of age. Since then, based on additional data, it has also been approved for the prevention of vulvar and vaginal cancer, and for the prevention of genital warts in boys and men between nine and 26 years of age. Now, new data have led a Food and Drug Administration advisory panel to recommend expanding the vaccine’s use to include the prevention of anal cancer, a disease whose incidence doubled in the United States between 1975 and 2007.
In a Phase III double-blind study of 4,065 males, participants randomly received either the vaccine or a placebo. About 15% of the study participants were men who have sex with men — a group considered to be at increased risk for anal cancer.
Over the course of the study, 12% of the men in the placebo group were diagnosed with anal intraepithelial neoplasia (AIN): abnormal cell development in the anus that, if left untreated, can eventually become anal cancer. In comparison, only 3% of the men who received the vaccine were diagnosed with AIN.
Although the study was limited to men between the ages of 16 and 26, it is expected that efficacy against anal cancer would also extend to a younger age group, as well as to women and girls. The panel stated that there’s no reason to believe the vaccine would work differently or be less effective against AIN or anal cancer in women.
The FDA must still make a final decision on whether or not to accept its panel’s recommendation, but usually follows these recommendations.
Sources and more information
“Approved Products: Human Papillomavirus Vaccine.” U S Food and Drug Administration. October 16, 2009. Accessed December 1, 2010. Available at http://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm172678.htm.
“Ask the Experts about Human Papillomavirus (HPV) Vaccines – CDC experts answer Q&As .” Immunization Action Coalition (IAC). July 2010. Accessed December 1, 2010. Available at http://www.immunize.org/askexperts/experts_hpv.asp.
Walker, Emily P. “Medical News: FDA Panel Endorses Gardasil for Anal Cancer.” MedPage Today. November 17, 2010. Accessed December 1, 2010. Available at http://www.medpagetoday.com/HematologyOncology/OtherCancers/23486.
Centers for Disease Control and Prevention Vaccine Information Sheet (VIS), HPV (human papillomavirus). http://cdc.gov/vaccines/pubs/vis/downloads/vis-hpv-gardasil.pdf. Accessed December 1, 2010.