Breast screening error—women need reassurance, not misleading statistics

May 7, 2018, Cancer Research UK
Credit: flickr CC-BY-2.0

On Wednesday, Jeremy Hunt announced that the English breast screening programme had suffered a computer failure, resulting in an estimated 450,000 women not receiving their final breast screening invitation since 2009. This has triggered widespread concern, and is being widely covered by the media.

In his announcement, the Secretary of State for Health and Social Care also said that between 135 and 270 women may have "had their lives shortened as a result" of the error. These numbers are estimates. But, more worryingly, that phrasing is now being reported as a fact of the number of lives lost, rather than an estimate. It's not possible to know for sure how accurate this figure may be, but talking about it in this way, before the findings of the independent inquiry into the error has even started, has served to stir fear.

That's why, for women who may have been affected, this announcement is causing worry and distress. And the latest reports of NHS helplines being inundated with calls backs this up.

How reliable is this estimate?

Professor of the Public Understanding of Risk, Sir David Speigelhalter, has pointed out that the 135-270 'lives shortened' claim is likely to be misleading. In part this is because the benefit of screening in older women is more controversial than in younger age groups.

There also isn't good evidence on what happens if a woman misses her last screen, but has attended previous ones – so it's unclear how much of an impact one missed screen might have. This of course should not take away from the fact that women affected have had their choice to participate in the screening programme taken away and, potentially, the chance to have a cancer diagnosed earlier than it would otherwise have been.

And as Speigelhalter says, screening comes with harms as well as benefits. The fact these harms may have been avoided for some women also needs to be considered. If we accept Jeremy Hunt's 270 lives shortened figure, Spiegelhalter estimates that "up to 800 women may have been saved from harm by not sending them their final screening appointment letter." [emphasis in original]

Credit: Cancer Research UK

This is down to overdiagnosis. While there's good evidence that the breast screening programme benefits women through early detection of breast cancers, screening also harms some of the women taking part. These women do not benefit from earlier detection of disease but instead have slow-growing, harmless breast cancers picked up through screening, when they would have otherwise gone undetected. For every 1000 women who take part in the UK screening programme, 5 will have their life saved, but 17 will be unnecessarily treated for a harmless cancer that would not have caused symptoms.

Overdiagnosis can become more likely when screening older women, as they have a shorter life expectancy and any cancer diagnosed early has less chance of becoming life-threatening. How the benefits of screening older women stack up against the harms of overdiagnosis and overtreatment isn't clear, which is why, when there aren't any IT errors, the UK screening programme stops inviting women at age 70.

The role of the AgeX clinical trial?

AgeX, the age extension trial, which in part helped to uncover the algorithm failure, aims to understand more about screening (as well as women from age 47-49). Public Health England set up this trial to gather better data to inform the breast screening programme and the service it should offer to women.

Some have taken aim at this study as being to blame for the error. But this thoughtful piece from The Guardian, examining the validity of the "270 deaths" figure as well as the estimate that 450,000 women have been affected, says otherwise.

Among all this debate, it's important not to lose sight of the alarm caused to women and their families – and heightened by the rhetoric in the media. We need to understand what the actual impact may have been, which is the job of the independent inquiry that has been set up to study individual medical histories of the women affected.

But even then, it may be hard to find out what might have happened had this failure not taken place. In part because it is incredibly difficult to unpick what could have happened to each individual woman, as well as the difficulty in pinning down the precise benefits that final breast screening appointment may offer.

The breast screening programme has been set up to offer women aged 50-70 screening, and it failed to do that for some in their final screening round. Thousands had a choice they should have been afforded taken away from them. But breast isn't perfect, and the issue is more complex than simple but alarming headlines might lead us to believe.

Explore further: UK: 450,000 women missed out on breast cancer test

Related Stories

UK: 450,000 women missed out on breast cancer test

May 2, 2018
Britain's health minister apologized Wednesday for what he called a "serious failure" that resulted in hundreds of thousands of women in England not being invited to a screening test for breast cancer.

Why are women at high breast cancer risk not having supplemental MRI screening?

March 19, 2018
Women at high lifetime breast cancer risk might benefit from breast MRI screening in addition to routine mammography, but a new study shows that breast MRI is greatly underutilized even though access is widely available. ...

Screening has had 'little impact' on falling breast cancer deaths in the Netherlands

December 5, 2017
Breast screening in the Netherlands seems to have had a marginal effect on breast cancer mortality over the past 24 years, suggests research in The BMJ today.

Some women still don't underststand 'overdiagnosis' risk in breast screening

August 28, 2014
A third of women who are given information about the chance of 'overdiagnosis' through the NHS breast screening programme may not fully understand the risks involved, according to research published in the British Journal ...

Low awareness of breast cancer overdiagnosis and overtreatment among US women

September 14, 2017
Did you know that routine mammograms can lead to overdiagnosis and overtreatment of breast cancer? Most American women aren't aware of these risks of breast cancer screening, reports a study in the October issue of Medical ...

Women with disabilities may be missing out on cancer screening

September 28, 2017
Women with disabilities are a third less likely to participate in breast cancer screening and a quarter less likely to take part in bowel cancer screening compared to women reporting no disabilities, according to a new paper ...

Recommended for you

Targeting the engine room of the cancer cell

June 18, 2018
Researchers at Columbia University Irving Medical Center (CUIMC) have developed a highly innovative computational framework that can support personalized cancer treatment by matching individual tumors with the drugs or drug ...

Researchers create novel combination as potential therapy for high-risk neuroblastoma

June 18, 2018
Researchers at VCU Massey Cancer Center in Richmond, Virginia, have identified a promising target to reverse the development of high-risk neuroblastoma and potentially inform the creation of novel combination therapies for ...

Study suggests well-known growth suppressor actually fuels lethal brain cancers

June 18, 2018
Scientists report finding a potentially promising treatment target for aggressive and deadly high-grade brain cancers like glioblastoma. But they also say the current lack of a drug that hits the molecular target keeps it ...

Standard myelofibrosis drug can awaken 'dormant' lymphoma

June 18, 2018
Most patients with myelofibrosis, a rare chronic disorder of the haematopoietic cells of the bone marrow, benefit from drugs from the JAK2 inhibitor class: symptoms are relieved, survival extended and general quality-of-life ...

Genomics offers new treatment options for infants with range of soft tissue tumors

June 18, 2018
The genetic causes of a group of related infant cancers have been discovered by scientists at the Wellcome Sanger Institute, the University of Wuerzburg and their collaborators. Whole genome sequencing of tumours revealed ...

Breast cancer researcher warns against online genetic tests

June 18, 2018
We have never been so fascinated by the secrets inside our cells.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.