Merck & Co's Gardasil vaccine won US approval for preventing anal cancer.
Both the drugmaker and the US Food and Drug Administration announced the approval, which applies to people ages 9 to 26.
Gardasil already is approved for the same age population for the prevention of cervical, vulvar and vaginal cancers.
It fights infection with the sexually transmitted human papillomavirus (HPV), which also can lead to cancers of the anus, penis, head and neck.
As of the end of May 2010, more than 65 million doses of Gardasil had been distributed worldwide since its approval in 2006.
Anal cancer is one of the one of the less common types of cancer, with an estimated 5,300 new US cases diagnosed each year, but the incidence is increasing, the FDA said.
"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," said Karen Midthun, director of the FDA's Centre for Biologics Evaluation and Research.
The FDA cited data showing Gardasil was effective in a study of men who have sex with men, a group that has a higher incidence of anal cancer.
The agency said that because anal cancer is the same disease in males and females, such data can support the use in females as well.
(Reuters Health, Lewis Krauskopf, December 2010)