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Prepare for a sea change in how we assess the risk of breast cancer screening

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The Marmot review is in. Breast screening has now been officially recognised in the UK to be a mixed bag, with the potential for benefit but also the risk of harm through overdiagnosis and overtreatment.

This is nothing new; it's been available via Cochrane for years.1 But this recognition for British women marks a significant change in how we view screening. It tells us what we already know - except now it is on the front page of the tabloids. Screening can cause harm.

From antibiotics to statins and the last stages of life, GPs deal in uncertainty. We are versed in the weighing of unknowns against each other. Sharing decisions where there is often no correct answer is an aim of contemporary general practice; indeed, the GMC says doctors should ‘provide effective treatments based on the best available evidence’ and ‘give patients information they want or need in a way they can understand; respect patients' right to reach decisions with you about their treatment
and care.’2

Yet the immediate response of Breakthrough Breast Cancer, the Breast Cancer Campaign, and Breast Cancer Care was to join together and say that the review had brought ‘much needed clarity- screening can save lives’.3

They added: ‘This is good news for women as they can now be assured that breast screening can be beneficial... some women who attend screening may be diagnosed and treated for a cancer that may not have caused them harm in their lifetime... We encourage all women to attend their screening appointments.’4

I find this amazing, in a sad way. The cancer charities are thus making a value judgement that women should take part in a program which, the review found, gives a 43 in 10,000 chance over 20 years of delaying your death due to breast cancer - and which will overdiagnose 129 women over the same period, thus exposing them to treatment they cannot benefit from.5 The chance of being harmed
by unnecessary treatment is far more than the chance of extending life due to the screening; for every death delayed from breast cancer, three women are treated unnecessarily.

So what should women do? If we really mean what we say by informed choice, we must allow women the autonomy to decide for themselves. This includes the right for women to make choices that their doctor - or the director of a charity-  might personally disagree with.

So are these large cancer charities are best placed to inform women of their options? Only one UK charity that I know of, the small Challenge Breast Cancer in Scotland, has long called for fair information on screening to be given to women.

For despite the enormous amount of 'awareness' about breast cancer, most women do not know that age is a large risk factor for breast cancer and most overestimate the benefit of mammography.6,7 We have to stop focussing on the throwaway advertising lines which 'awareness' campaigns ride on, and concentrate on evidence-based knowledge.

Some women will have rotten bad luck and have breast cancer with no apparent risk factors. But how many other women know about the effects of being overweight or excess alcohol on cancer risk; and how much investment is going into reducing population risks through evidence-based legislation on food or alcohol? I'm concerned that we have been 'pinkwashed' by screening, which has been oversold to the extent that we are overlooking other interventions which could be less harmful and more beneficial.

It is now up to the UK National Screening Committee to evaluate the cost effectiveness of breast screening. They will no doubt bear in mind that the review was clear that their numbers were best estimates, not proven facts; that they focussed on breast cancer rather than all cause mortality, which can overestimate screening benefit; and they will also know that the trials they focused on are up to two decades old, which means that the effect of newer, better breast cancer treatments isn't going to be visible, and may produce different screening effects.

The Informed Choice about Cancer Screening consultation is due to report in November and is likely to herald a sea change in how we describe risk and benefit to patients, via new, evidence-based information leaflets. And I predict then GPs will be busy doing what they do best: helping people deal with uncertainty as best, and as independently, as we can.

References

1 The Cochrane Library. Screening for breast cancer with mammography. 2008. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD001877.pub4/abstract
2 The GMC. Good Medical Practice: Providing good clinical care. http://www.gmc-uk.org/guidance/good_medical_practice/good_clinical_care_inde
x.asp

3 The GMC. Good Medical Practice: Duties of a doctor. http://www.gmc-uk.org/guidance/good_medical_practice/duties_of_a_doctor.asp
4 The Breast Cancer Campaign. http://www.breastcancercampaign.org/
5 Independent UK Panel on Breast Cancer Screening. The benefits and harms of breast cancer screening: an independent review. The Lancet 2012. http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)61611-0/abstract
6 Moser K. Do women know that the risk of breast cancer increases with age? BRCGP 2007. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2047017/?tool=pubmed
7 Dominighetti G et al. Women’s perception of the benefits of mammography screening: population-based survey in four countries. Int J Epidemiol 2003. http://ije.oxfordjournals.org/content/32/5/816.long

Readers' comments (13)

  • Mark Struthers

    Professor Peter Gotzsche of the Nordic Cochrane Centre has produced a newly updated leaflet on ‘Screening for Breast Cancer with Mammography’.

    http://www.cochrane.dk/screening/mammography-leaflet.pdf

    At the end of the summary he writes,

    “It therefore no longer seems reasonable to attend for breast cancer screening. In fact, by avoiding going to screening, a woman will lower her risk of getting a breast cancer diagnosis. However, despite this, some women might still wish to go to screening.”

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  • I'm 100 percent in favour of women being given more accurate information that is the case now. The problem is that the information that can be given is inadequate for a rational decision to be made.

    The problem surely is that, in the present state of knowledge, we simply don't know enough for women, or their GPs, to make a rational decision.

    How are you to advise a woman with a lump when there is no way to be sure whether it will sit there or kill her? Would you advise her to have a mastectomy just in case, or would you advise her to chance it?

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  • Colqhuon misses the point, as will all the other armchair commentators without expereience of front line medical practice.

    He appears to intimate the accuracy of information prior to this new report made it easier to make a rational decision (to undergo mammography).

    He even appears to raise the ancient hysterical chestnut questioning whether women can be rational or GP's make decisions...........

    He is however able to identify the problem being our state of knowledge and glibly invokes medical advice as arbiter, rather than informed consent from a patient who, in law, has the absolute right to decide how they and their body are treated.

    How would he advise someone with odds of 4 to 1.3 their lump is safe? (the stats appear to be for 1,300 women with cancer 4,000 more were treated unnecessarily which is hardly equivalent to either' sit there or kill her' by any means of scientific interpretation).

    At least Peter Gotzsche at Cochrane supports womens' freedom to their own rational individual choice.

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  • Mark Struthers

    Margaret asks,

    "So what should women do?"

    Many of Margaret's women patients will ask her what she would do. What will you do, Margaret, when you get the call for screening?

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  • Bertrand Russell once said that we should learn to live with uncertainty yet not be paralysed into inaction.
    If nothing else the Marmot report has shifted the bigoted certainties of the screening zealots into the healthy arena of uncertainty. This now sets the agenda for action. First we must demand the hidden information on all cause mortality in the old trials of screening. My hunch is that screening doesn't save lives but merely exchanges the cause of premature deaths. Second we must try and learn about the natural history of screen detected DCIS and the only way to do that is an RCT of surgery versus active monitoring exactly like the ProtecT trial of PSA detected prostate cancer. In the meantime GP as always will have to manage the uncertainty in practice and if they were all like Margaret McCarty they would be in good hands.

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  • Dear David
    breast LUMPS are symptoms - screening DOES NOT apply. Screening is ONLY for people with no symptoms of disease. The stats can't be mixed.
    The issue for women will be how to examine the statistics for benefit and harm and make a rational choice before having screening, or not.
    We do this for just about every other medical intervention. We can do it for screening too - but it has to be about individual choice.

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  • I take McCartney's point. But I like Michael Baum's contribution. It was very clear that present information given to women is dangerously incmplete, and thanks to the hard work of Baum and McCartney it seem that that will be remedied. But as Baum points out the data simply aren't there for women to make a rational choice or for doctors to give sound advice. Let's hope that changes, but in the meantime it should be admitted openly.

    [I'll ignore the rather incoherent rant of the ubiquitous Dr. Sikorski. Anyone who thinks it is ethical to treat patients with sugar pills should be answering to the GMC, not me. Some of them have been. I do hope that the Wadhurst practice gets proper informed consent before exposing patients to your rather bizarre views about medicines that contain no medicine.]

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  • I agree - and the important bit in the review is the fact that the trials are 20 years old, do NOT look at all cause mortality, and "However, given the uncertainties around all of these estimates, the Panel state that the figures quoted give a spurious impression of accuracy, and further research will be needed to more accurately assess the benefits and harms of breast cancer screening." too right

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  • So are these large cancer charities best placed to inform women of their options?

    The answer is very firmly NO - they have a vested interest - they raise more money by increasing the scaremongering .

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  • Mark Struthers

    Margaret says,

    "The issue for women will be how to examine the statistics for benefit and harm and make a rational choice before having screening, or not."

    It is impossible for an individual to make a 'rational' choice about screening ... and I believe it is dishonest to suggest that it is.

    PS. Colquhoon's coherent irrationality is everywhere: ignore it, one can't.

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