I’ve written several times on this site about the practice of mammography. In short, here’s what I believe to be true:
- mammography is marketed to women as a bit of a ‘no-brainer’ – it’s effective for picking up breast cancers earlier than they would be otherwise, saves lives, and women would be mad not to attend.
- mammography is actually not very good at saving lives, and many, many women need to be screened to prevent one death.
- mammography has hazards, including the fact that it picks up cancers that would never have bothered women if left alone, and therefore opens up the risk of unnecessary investigation and treatments (over-diagnosis).
The British Government has been sternly criticised by some researchers who claim it continues to mislead women about the benefits and harms of mammography. See here for more on this.
Now, the issue has really blown up on the publication, this week, of an open letter from a female doctor to Mike Richards – Britain’s ‘cancer tsar’. In this letter, published on-line in the British Medical Journal, Dr Susan Bewley, takes Richards to task over the lack of transparency regarding the pros and cons of mammography [1]. Here’s some excerpts from her letter.
I declined screening when it was offered, as the NHS breast screening programme was not telling the whole truth. As a non-expert in the subject, I found myself examining the evidence for breast screening with increasing doubts. I compared the NHS and Nordic Cochrane Centre leaflets and found that the NHS leaflets exaggerated benefits and did not spell out the risks. Journals showed a reputable and growing body of international opinion acknowledging that breast cancer screening was not as good as used to be thought. The distress of overdiagnosis and decision making when finding lesions that might (or might not) be cancer that might (or might not) require mutilating surgery is increasingly being exposed. The oft repeated statement that “1400 lives a year are saved” has not been subjected to proper scrutiny. Even cancer charities use lower estimates. I expressed my misgivings to you “behind the scenes” as a work colleague. You replied in a personal email “that the large majority of experts in this country disagrees with the methodology used in the Cochrane Centre reviews of breast screening.
Women should be reassured that the NHS treats breast cancer more successfully now, but screening is only of marginal benefit, at best. The medical profession needs to find ways to cope with the complex issues. Trust is at stake if the public is not told the full story. In the past few years British women have not been told about the genuine doubts. Those millions of women passing through the breast screening treadmill have been unaware of the problems, criticism, and real numerical risks they face.
Susan Bewley goes on to say:
It’s uncomfortable to change set beliefs in the face of changing evidence but unforgivable not to. I am not convinced that you have challenged your experts competently and mercilessly, rather than hidden behind them. Thus I support the calls for an independent review of the evidence—a real, unbiased review that will not be kicked into the long grass, whose findings will be widely and properly disseminated, and that will adjust screening policy appropriately and will lead to proper pursuit of the research implications.
Mike Richard’s response [2], published the same day in the BMJ, informs us that an independent review is underway, and that:
Should the independent review conclude that the balance of harms outweighs the benefits of breast screening, I will have no hesitation in referring the findings to the UK National Screening Committee and then ministers. You also have my assurance that I am fully committed to the public being given information in a format that they find acceptable and understandable and that enables them to make truly informed choices.
I like the sound of an independent review, but I was a little concerned by Mike Richard’s comment that:
I will do my best to achieve consensus on the evidence, though I realise this may not ultimately be possible.
This, of course, opens the door for some more mealy-mouthed rhetoric. But, on the face of it, the British Government appears to be doing the decent thing over mammography. And at the end of the process, I hope very much that women will have more clarity over its benefits and harms, and as Mike Richards says, will enable women to make ‘truly informed choices’. Once truly informed, though, let’s not be too surprised if large swathes of women decide that mammography is not the no-brainer women have generally been led to believe it to be.
References:
1. Bewley S. The NHS breast screening programme needs independent review. BMJ 2011;343:d6894
2. Richards M. An independent review is under way. BMJ 2011;343:d6843
