UK doctors are urging young women to come forward to test a vaccine against cervical cancer.
A vaccine could be available in a few years
They are looking to recruit 300 women aged 15-25 to join a total of 13,000 female volunteers worldwide.
Early trials have shown a jab can offer 100% protection against strains of wart virus linked to about 70% of cervical cancers.
The future hope would be to vaccinate girls before they are sexually active, raising ethical issues, said doctors.
Both GlaxoSmithKline and Merck Sharp & Dohme have developed vaccines against 'high risk' strains of human papilloma virus (HPV) and are in a race to get their products approved.
Cancer Research UK's Dr Anne Szarewski, is one of the team recruiting women to trial GSK's vaccine.
Half of the women will receive three doses of the HPV vaccine over six months, while half will receive 'control' vaccines against hepatitis A.
Women who have previously been immunised against hepatitis A or those who are pregnant should not volunteer.
Advertisements have been placed in newspapers asking for women to come forward and take part in the trial.
Dr Szarewski said: "We hope it will offer lifelong protection against cervical cancer.
"It would be a huge advance. Cervical cancer is the second biggest cause of cancer death in women worldwide."
She believes such a vaccine will be on the market within the next few years.
But she questioned whether there would be the political environment in which to implement such a vaccine.
"The issue is not whether it will be available, but the controversy over whether anyone would want to give it to their daughters.
"We are talking about vaccinating young girls against what is effectively a sexually transmitted infection."
Richard Winder, deputy director of the NHS Cancer Screening Programmes, said: "We are following the trials of HPV vaccines and will monitor the results.
"However, there is still much research to be done before we can determine the potential role HPV vaccination may play in preventing cervical cancer."