Twice as many lives saved than overdiagnosed by breast screening

For every woman overdiagnosed by breast screening, two deaths will be prevented, according to scientists at Queen Mary, University of London.

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Following controversial debates in recent months over the risks and harms of screening for breast cancer, the researchers, part funded by Cancer Research UK, set out to uncover how effective the programme is at saving lives.

Some reports had estimated that for every life saved, six women were overdiagnosed. Overdiagnosis describes cancers picked up and treated as a result of screening which would not have been diagnosed in a woman’s lifetime had screening not taken place.

The researchers say these latest figures show that it is worth going for screening. Stephen Duffy, Professor of Cancer Screening at Queen Mary’s Wolfson Institute of Preventive Medicine, said: “This shows that the benefits of screening outweigh the harms.

“Unfortunately, we haven’t yet got a flawless screening test, and some cases that are picked up wouldn’t have needed treatment. But for every case like this, screening saves two women who would have otherwise died from breast cancer.

“If a tumour is detected through screening it is important to consider a range of options before treatment begins. Women should be given the opportunity to understand the implication of their screening results and discuss their treatment options with a specialist.”

The researchers carried out two studies. One study predicted the number of women who would have died from breast cancer in the UK if the screening programme had not been introduced.

The other study looked at the number of deaths from breast cancer in 80,000 women in a randomised trial in Sweden, comparing those who were offered screening with those who were not.

Dr Lesley Walker, director of cancer information at Cancer Research UK, said: “The National Breast Screening Programme saves lives, so we encourage women to go when invited.

“All women should have access to high quality information and advice to help them make decisions that are appropriate to their individual condition. It’s standard practice to have these discussions which help women make the choice that’s right for them, so overdiagnosis need not be a reason to feel worried about going for screening.

“As well as attending screening, we would encourage all women to be breast aware and to go to their doctor if they notice any unusual changes to their breasts.”


Absolute Numbers of Lives Saved and Overdiagnosis in Breast Cancer Screening, from a Randomised Trial and from the Breast Screening Programme in England. Duffy et al. Journal of Medical Screening.

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Joel Winston
Faculty Communications Manager (Medicine and Dentistry)