A vaccine that targets a human wart virus has completely prevented early-stage cervical cancer and precancerous lesions in women caused by the two most common forms of the virus.
"This trial confirms that a vaccine can give young women a high level of protection from developing precancerous lesions and early cervical cancers," said Laura Koutsky, a professor of epidemiology at the University of Washington, who led the study.
The ability to prevent cervical cancers, at least for the short term, was shown in a late-stage trial sponsored by the US drug maker Merck. It included more than 12,000 women from 13 countries, aged 16 to 26, who were not infected with either of the virus types when the trial began.
The two forms of sexually transmitted human papillomavirus, types 16 and 18, are responsible for an estimated 70 per cent of cervical cancer cases and are the targets of Merck's Gardasil vaccine.
Such cancers kill about 300,000 women worldwide each year.
The cancer vaccine also protects against genital warts.
Half the women in the Phase III trial received three doses of Gardasil over a six-month period, while the other women received placebos. The women were then followed for an average of 17 months.