The U.S. Food and Drug Administration approved Gardasil “for the prevention of anal cancer and associated precancerous lesions due to human papillomavirus (HPV) types 6, 11, 16, and 18 in people ages 9 through 26 years.” Gardasil is already approved for the same age population for the prevention of cervical, vulvar, and vaginal cancer and the associated precancerous lesions caused by HPV types 6, 11, 16, and 18 in females.  It is also approved for the prevention of genital warts caused by types 6 and 11 in both males and females. Karen Midthun, M.D., director of the FDA’s Center for Biologics Evaluation and Research, commented, “Treatment for anal cancer is challenging; the use of Gardasil as a method of prevention is important as it may result in fewer diagnoses and the subsequent surgery, radiation or chemotherapy that individuals need to endure.” The FDA said that Gardasil’s ability to prevent anal cancer and the associated precancerous lesions [anal intraepithelial neoplasia (AIN) grades 1, 2, and 3] caused by anal HPV-16/18 infection was studied in a randomized, controlled trial of men who self-identified as having sex with men (MSM). This population was studied because it has the highest incidence of anal cancer. At the end of the study period, Gardasil was shown to be 78 percent effective in the prevention of HPV 16- and 18-related AIN.  Because anal cancer is the same disease in both males and females, the effectiveness data was used to support the indication in females as well, the FDA said.

http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm237941.htm