A vaccine that prevents infections known to cause cervical cancer could be available to women within three years, UK experts believe.
Smear tests can spot cancer
By guarding against human papilloma virus, it could save thousands of lives and may end the need for smears tests.
The vaccine would be given to girls before they are sexually active.
Trials have shown a jab can offer 100% protection against strains of HPV linked to about 70% of cervical cancers.
Some forms of the HPV virus only cause genital warts, but others cause cervical cancer.
It is estimated up to half of the young women in Britain have been infected with a high-risk strain of HPV by the time they are 30.
'High risk' HPV types, strains 16, 18 and 31 and 33, have been found to be present in close to 100% of all cervical cancers, according to the NHS Cancer Screening Programmes.
Since cervical cancer is the second most common cause of cancer death in women worldwide, preventing HPV would save many lives.
Both GlaxoSmithKline and Merck Sharp & Dohme have developed a vaccine against HPV and are in a race to get their products approved.
The two vaccines are being tested in thousands of women around the world, including the UK.
These will seek to confirm the vaccines' effectiveness and safely.
Cancer Research UK's Dr Anne Szarewski, who is trialling GSK's vaccine in the Margaret Pyke Centre in London, said experts hoped that a course of three injections over six months could provide life-long immunity.
She said: "We know that certain types of the HPV virus, which is sexually transmitted, are the main cause of over 99 per cent of cervical cancer cases.
"With any disease caused by a virus, the best way to stop it is to prevent it with a vaccine.
End to smears?
"I do feel that the work we are doing on this vaccine is the most exciting development in cervical cancer research in many years.
"This research is promising and could result in almost completely preventing cervical cancer.
"The vaccine may even eventually mean the end of smear testing.
But she cautioned: "It is early days and the vaccine is still being researched and will not be available for a few years."
Under the national screening programme, women aged 25 to 64 are invited to have a smear test every three to five years, depending on their age.
Julietta Patnick, director of the programme, said: "The NHS Cervical Screening Programme is alert to the trials of HPV vaccines for cervical dysplasia and will monitor the results.
"As the developers acknowledge, however, there is still much research to be done before we can determine the potential role HPV vaccination may play in preventing cervical cancer.
"The NHS Cervical Screening Programme is highly successful, saving around 4,500 lives every year in England.
"I strongly urge all women to continue to attend for regular cervical screening."
A spokesman from GlaxoSmithKline said the company planned to submit an application to the Medicines and Healthcare products Regulatory Agency in 2006 in the hope that its vaccine Cervarix could be made available in 2007.