Britain's cervical screening programme is helping save the lives of 5,000 women a year and has prevented a cancer epidemic, experts reveal today.

National screening for cervical cancer started in 1988 after deaths from the disease among women aged under 35 increased three-fold in the previous 30 years.

Now researchers have estimated that the lives of 100,000 women born between 1951 and 1970 will be saved thanks to screening. Writing in The Lancet, they said that 15 years ago the country was heading for a devastating outbreak of the disease.

But since the introduction of screening, that trend has been reversed, at a cost per life saved of about £36,000. The research compared falling death rates from cervical cancer since 1988 against the projected increase if screening had not been introduced.

Professor Julian Peto, who led the study for Cancer Research UK, said that changes in sexual behaviour since the 1960s led to epidemic levels of sexually transmitted diseases.

This meant that the HPV (human papillomavirus) infection - which can go on to cause cervical cancer - became more common among sexually-active women.

Up to half of young women in Britain have been infected with a high-risk strain of HPV by the time they are 30.

The virus usually clears up on its own but if it persists it can lead to changes in the cells in the cervix which may lead to cancer if untreated.

These early changes can be detected with screening and the abnormal cells removed, preventing cancer from developing.

The researchers said the increased prevalence of HPV was presumably the main reason for the rapid increase in cervical cancer deaths in the 1960s to 1980s, but other factors included age when a woman first had sex, the number of sexual partners, growing numbers of sexual diseases, smoking and contraceptive use.