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.
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