By Dr Emma Pennery
Since screening programmes were established around thirty years ago, there has been a lot of public debate, often sharply polarised, over the benefits and harms of breast screening.
The results of an independent breast screening review, commissioned by Cancer Research UK and the Department of Health, were published in the Lancet earlier this week.
Professor Sir Mike Richards, national cancer director and Dr Harpal Kumar, chief executive officer of Cancer Research UK, tasked Professor Sir Michael Marmot with chairing a panel of experts to examine the evidence in the context of the UK programmes. Over the last year, the group has carried out a thorough review. All the trials included were 20-30 years old but nevertheless they were chosen as they represented the best evidence available.
The reviewers concluded the screening programmes do save lives but at a cost. They estimate that for every 235 women invited for routine screening between the ages of 50 and 70, (and for every 180 women who attend screening), one breast cancer death would be prevented. This amounts to 1,300 deaths prevented through breast screening per year.
But at the same time they also concluded that screening can result in over-diagnosis, with about 4000 women each year aged between 50-70 having treatment for a condition that would not have caused a problem in that woman’s lifetime.
Importantly, no individual woman (or their doctor) can know if a breast cancer found at screening was over diagnosed (so would have remained undetected and/or unthreatening throughout her lifetime). Nor will she know if she survives breast cancer, whether it was because of screening.
At present, doctors cannot reliably tell whether a breast cancer, whether found through screening or not, is going to be fatal, so treatment is likely to be recommended.
To put it in a bit more context, of the approximately 307,000 women aged 50-52 years who are invited to begin screening every year, just under 0.5 % (1307) will be prevented from dying from breast cancer and just over 1% (3971) will have an over-diagnosed cancer during the next 20 years.
The review panel recommends breast screening continues but with improved information to better convey to women the benefits and harms.
Breast Cancer Care responded, along with the other breast cancer charities. We believe that the review has provided clarity that screening can save lives. We encourage all eligible women to consider attending.
We think it’s extremely important that women can access clear and balanced information on the benefits and harms of breast screening so that they can make an informed decision about attending.
The Department of Health has said that its top priority is to review and update the existing information that women receive to make the pro’s and cons clear. We urge them to do this as soon as possible.
Dr Emma Pennery is clinical director and head of healthcare professional training at Breast Cancer Care.
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By Dr Emma Pennery