Breast screening

Thousands of women in England could be undergoing unnecessary and potentially devastating treatment for suspected breast cancer, said the study from researchers at the Nordic Cochrane Centre.

They looked at seven trials investigating both the benefits and negative outcomes associated with breast screening.

They found that for every 2,000 women invited to have mammograms, one would have their life prolonged but 10 would endure potentially devastating and unnecessary treatment.

And another 200 of those women would experience weeks or months of anxiety because of "false" positive findings - the discovery of cell changes that later turned out to be benign.

Between 2003 and 2004, 1.4 million women in England were screened for breast cancer, of whom more than 11,000 had cancers diagnosed. The annual cost of the programme is £75 million.

Professor Michael Baum, professor emeritus of surgery and visiting professor of medical humanities at University College London, told the Daily Telegraph that until now his position was that women should make an informed choice based on the facts.

But he added: "This latest evidence shifts the balance even further towards harm and away from benefits.

"If this report stands up, the NHS screening programme should be referred to the National Institute for Clinical Excellence to decide whether it should be closed down."

Professor John Toy, medical director of Cancer Research UK, added: "Researchers in the field all agree that breast screening saves lives although they differ in their views about the balance of the pros and cons.

"Benefits need to be balanced against any disadvantages, as is the case with all medical treatments.

"Certainly women invited for screening should be made aware of both potential benefits and downsides - such as possible initial mis-diagnosis. But overall we continue to encourage UK women to participate in the NHS Breast Screening Programme."

Julietta Patnick, director of NHS Cancer Screening Programmes, said over-diagnosis was "a fact" but that screening still saved lives.