Debate on breast screening 'should not distract from the benefits' says Cancer Research UK

In collaboration with the Press Association

The debate over the precise number of women saved by breast screening should not distract people from the fact that it saves lives, say experts from Cancer Research UK.

Responding to an article in the journal BMC Medical Informatics and Decision Making questioning benefits of breast screening, Cancer Research UK's chief clinician and senior epidemiologist both pointed out that thousands of lives had been saved since the screening programme was introduced.

In the BMC article, Dr John Keen from the John Stroger Jr Hospital of Cook County, Chicago and Dr James Keen from the University of Nebraska argue that too little attention has been paid to the number of lives breast screening actually saves.

Drs Keen and Keen used three different methods to calculate the possible benefits of screening and concluded that the lifesaving benefit increases slightly with age, as does the death risk among women who do not attend screening.

But according to their calculations, for every 1,000 women over the age of 50 who are regularly screened for 15 years, about 1.8 lives are saved - a lower estimate than previous calculations.

They also calculate that women at age 40 have a 99.5 per cent chance of not dying from breast cancer before age 55, which improves to 99.6 per cent with regular screening - an increase in survival of just 0.1 per cent.

But Cancer Research UK's Professor Stephen Duffy, who runs the Cancer Screening and Aetiology Group at Barts and The London, has written an accompanying commentary in which he urges experts to look at real-life statistics rather than modelled estimates when determining the value of breast screening.

Professor Duffy makes two key points in his commentary, the first of which relates to the paper's focus on the large number of women who must be screened in order to save a life.

He points out that this is the case with vaccination, cervical screening and many other disease prevention strategies, and that "if one is in the business of preventative medicine, one has to accept this as a fact of life."

Professor Duffy's second argument relates to the "questionable" accuracy of the figures contained in the study.

He argues that, rather than arriving at figures via mathematical modelling, it might be better to trust direct results from real-life measurements, such as those collected during randomised trials of breast screening, which indicate that the number of lives saved is actually three times the figure calculated in the paper.

Professor Peter Johnson, Cancer Research UK's chief clinician, said that any debate about the details "should not be allowed to distract anyone from the benefits of breast screening, which is estimated to save more than 1,400 lives each year in England alone".

"Screening offers the best possible opportunity for early diagnosis of breast cancer and experts agree that this means a better chance of successful treatment," he explained.

"The information women receive at time of screening is based on careful research into the views of the women being screened. Improvements can always be made and we are contributing to a review by the Department of Health.

"There are still some uncertainties about predicting the precise risk of developing breast cancer and, although survival rates have increased greatly, 12,500 women still die of the disease each year in the UK.

"Too many women over 50 are already not attending their screening appointments. No one should be put off breast screening. It could save your life."