What’s a conflict of interest when it comes to breast screening?

The medical press is carrying a lot about the latest international arguments about breast screening. The BMJ carried an excellent editorial ‘Mammography wars” highlighting the recent Canadian taskforce on the subject. This called for a halt to routine breast examination, and a starting age of 50 before starting screening mammography, which they recommended to be done every 2-3 years. The other issue, is of course, Mike Richards review of NHS Breast Screening (which I am concerned is deeply biased towards screening from the start.) Then there was a paper from  Karsten Jørgensen, John D. Keen, and Peter Gøtzsche; the first and last authors are from the Nordic Cochrane group. They wrote “Proponents of mammographic screening generally say that the benefit is large and established beyond doubt, that there is little overdiagnosis, and that screening leads to less invasive treatment. The truth is that the benefit is doubtful, that overdiagnosis is substantial and certain, and that screening increases the number of mastectomies performed”.

To hot it up to blazing was a letter in the Lancet a couple of weeks ago, from a variety of doctors involved with screening which started

“Although the wider scientific community has long embraced the benefits of population-based breast screening, there seems to be an active anti-screening campaign orchestrated in part by members of the Nordic Cochrane Centre. These contrary views are based on erroneous interpretation of data from cancer registries and peer-reviewed articles. Their specific aim seems to be to support a pre-existing opposition to all forms of screening”.

I wonder if they mean me. Am I in a gang? How exciting. They go on

“We consider the interpretation by Jørgensen, Keen, and Gøtzsche, of the balance of benefits and harms to be scientifically unsound. Women would be better served by focusing efforts on how best, and not whether, to provide breast screening….

Organised, high-quality breast screening is an important public health initiative by numerous governments worldwide. These policies are based on robust and extensive analysis of individualised patient data from scientific trials, with particular attention paid to the balance of potential benefits and harms.To imply that such an international action is mass misrepresentation, or that screening is done for the benefit of self-interested professionals, is as perverse as it is unjustified..
The signatories below, charged with provision and implementation of breast screening in many different countries, remain convinced that the scientific foundation for population-based, quality-assured, organised breast screening is one of the major accomplishments of the translation of clinical cancer research into public health practice. Early detection, in combination with appropriate treatment, significantly lowers breast cancer mortality and improves the life quality of patients with the disease”.
It’s interesting that the authors of this full-on Lancet letter say that they have ‘no conflicts of interest’.
In medical journal terms, this usually means financial  interests. Now, I’m not saying that I think the authors of the Lancet letter have undeclared conflicts of interest. What I’m interested in is whether there are other ‘conflicts’ that we don’t often speak about and which may or may not affect the way we view things.
For example, if I have been particularly impressed by a teacher I’ve had, I may want to keep giving a treatment he taught me to do, even if evidence comes out saying that he was wrong. I may find it hard to believe he was wrong, and search for reasons to justify my practice. Is that a conflict ? Maybe. Perhaps not a ‘conflict’ as meant in the declaration at the bottom of journal articles, but it may mean that I approach the subject with some bias.
(Repeat: I am not charging the authors of the Lancet letter with bias; I am exploring the topic more generally.)
The Cochrane Nordic Centre employ doctors who have no attachments to screening services, and whose income does not derive from whether or not they recommend more screening, less screening, or no screening. They are paid to assess the evidence. The authors of the Lancet letter have interests in breast screening, as you would expect. Some work in private clinics which promote screening mammography. One such clinic’s website says “Our data shows that about 40% of new cancers seen at The London Breast Clinic are in patients under 50, the lower age level of the NHS Breast Screening Programme. Patients in the 3 Yearly NHS Breast Screening Programme, who wish for peace of mind, can receive annual imaging since it is widely recognised that many screen detected cancers have developed during this 3 year screening interval.” Another signatory is a medical advisor to a company making software for mammography. Others offer courses in breast screening. Others are in charge of national breast screening programmes.
Of course, it would be hard to take up these positions if you had doubt about the effectiveness of your intervention. In terms of independence, I struggle to see how evaluation of evidence is best done by people whose are most influential within a speciality. This is the same reason why doctors are often blinded when trials are done; the way we see things is sometimes altered by what we would like to believe.
None of this is an attack on the ethics of the people who signed the Lancet letter. I am trying to tease out why it might be important to have truly independent evaluations of evidence. The bottom line is that I think that’s what the Nordic Centre are delivering.


8 Responses to “What’s a conflict of interest when it comes to breast screening?”

  1. A Reader December 1, 2011 at 12:33 am #


  2. Ian Bright December 1, 2011 at 9:00 am #

    Margaret, in case you have not seen it (but I suspect you have) the issue of the usefulness of mammogrpahy has recently been a hot topic in the US. Google search the words New York Times Mammography and there are a series of links to articles and letters. The links are dated around 24 to 26 October 2011.

  3. Peter Martin December 2, 2011 at 9:22 am #

    I made some observations about non-financial conflicts of interest in a BMJ “Rapid Response” to an article about an entirely different subject three or four years ago. I attach a link in case it’s of any interest:


  4. Michael Baum December 2, 2011 at 2:02 pm #

    I have just read Peter Martin’s excellent letter to the BMJ where he describes “ideological” conflict of interest. I like that concept and confess that I suffer from a chronic ideological conflict of interest in pursuit of the numerical truths about the benefits and harms of screening. That COI of interest has done me no favours in political or financial terms but it’s real for all of that.

  5. Margaret McCartney
    margaretmccartney December 4, 2011 at 7:57 pm #

    Thanks Peter
    I think we all have potential of ‘conflicts’ – the issue is how easy or hard we would find it to walk away were we to find that our live’s work was no longer supported by evidence. I hope I would see this as a success – it’s always good to know what doesn’t work – and I hope, emotionally, I could stop investing in it.
    I have a great backup plan should general practice be proven to be harmful.

  6. Chris Hiley December 12, 2011 at 11:12 am #

    Following, as I do, the breast screening debate, your introduction of an ideological COI as something worth wondering about certainly chimes with me. As you know, I stare hard at the vice like grip of breast cancer charities on women’s model of ‘health in women’ and where risks lie. Whilst I don’t doubt those charities are good for women diagnosed with breast cancer I DO doubt they are an unequivocal good for women who do not have a cancer diagnosis (like me). I shall run off with your ideological Conflict of Interest notion, as Michael Baum labelled it in his comment, and write more about breast cancer charities and their Conflicts of Interest.

    Breast cancer charities awareness raising functions aren’t really about women’s health – whole women, if you will. If they were, they’d surely use breast cancer’s particular appeal to women to engineer wider conversations about heart disease or overweight, for example, and then explain breast cancer’s position amongst them. But they don’t. There’s a COI right there. And it’s the ‘usual’ financial version. Fundraisers and strategic concerns won’t sanction any mention of other health issues – there are rival charities for those and the money might go there.

    There are other COI’s for breast cancer charities in the screening debate. They REALLY NEED to hang on to screening as a ‘Call to Action’ for their own ends. If you have to say or imply how awful breast cancer is to raise funds (it is, and they do) you really need ‘an action’ to promote, as an answer to all the ‘what can I do to help myself?’ questions that come next.

    Breast cancer charities have a huge COI in managing their relationship with diagnosed women and their relationship with the much larger group of undiagnosed women in the general public. Both groups are considered stakeholders, I’m sure. The sector doesn’t manage that COI at all well. I suspect they don’t even see there is one.

    Unfortunately, breast screening sits right there, bang in the middle between the two.

  7. Derek Tunnicliffe December 12, 2011 at 6:56 pm #

    Hi Margaret. You should be interested in Tim Harford’s latest blog. OK, he’s an economist but his explanation of Baysian statistics helps explain the realities of breast cancer screening.

  8. Michael Baum December 14, 2011 at 5:33 pm #

    In response to Chris Hiley’s insightful comment here are the numbers.
    1 in 25 women die of breast cancer. That’s one too many but the answer is better treatment not screening.

    Five times more women die of cardio-vascular disease than breast cancer.

    If the money spent on screening (close on £100,000,000) a year was spent on women’s health more women would live longer healthier lives.

    COI- I’ve spent my life in the research and treatment of breast cancer and often the research was funded by the cancer charities who promote screening.