Breast Cancer Screening

jumpguy

Plenty of interesting controversy sprouting up nowadays about breast cancer screening doing more harm than good - especially with the advent of digital radiographs.

For those unfamiliar with the issue, here is a Cochrane review on the issue, and here is the plain language summary:

Screening with mammography uses X-ray imaging to find breast cancer before a lump can be felt. The goal is to treat cancer earlier, when a cure is more likely. The review includes seven trials that involved 600,000 women in the age range 39 to 74 years who were randomly assigned to receive screening mammograms or not. The studies which provided the most reliable information showed that screening did not reduce breast cancer mortality. Studies that were potentially more biased (less carefully done) found that screening reduced breast cancer mortality. However, screening will result in some women getting a cancer diagnosis even though their cancer would not have led to death or sickness. Currently, it is not possible to tell which women these are, and they are therefore likely to have breasts or lumps removed and to receive radiotherapy unnecessarily. If we assume that screening reduces breast cancer mortality by 15% after 13 years of follow-up and that overdiagnosis and overtreatment is at 30%, it means that for every 2000 women invited for screening throughout 10 years, one will avoid dying of breast cancer and 10 healthy women, who would not have been diagnosed if there had not been screening, will be treated unnecessarily. Furthermore, more than 200 women will experience important psychological distress including anxiety and uncertainty for years because of false positive findings.

Women invited to screening should be fully informed of both the benefits and harms. To help ensure that the requirements for informed choice for women contemplating whether or not to attend a screening programme can be met, we have written an evidence-based leaflet for lay people that is available in several languages on www.cochrane.dk. Because of substantial advances in treatment and greater breast cancer awareness since the trials were carried out, it is likely that the absolute effect of screening today is smaller than in the trials. Recent observational studies show more overdiagnosis than in the trials and very little or no reduction in the incidence of advanced cancers with screening.

In my experience, most of the public seem to be unaware of this issue. I'm not sure if patients are told about it before screening - anyone know?

So, are mammography screening's days numbered? I think the biggest barrier to that won't be the evidence against its favour but the public outcry. There are a few interesting initiatives taking off across the world, I read one on BBC news about blind people doing breast checks with the classic "feeling" method. I'm not aware of any major trials on alternatives to mammography (which is for lack of trying, I'm afraid my laptop is being difficult!)

echo beach

jumpguy wrote: »

In my experience, most of the public seem to be unaware of this issue. I'm not sure if patients are told about it before screening - anyone know?

This is the leaflet sent to women invited for screening. http://www.breastcheck.ie/sites/default/files/bc_appoint_nov07.pdf
There is no mention of possible downsides on it or in the frequent radio advertisements. There is more detail on the Breastcheck website but not near enough to allow an informed decision.

This article from The Lancet shows that fully informed women are less likely to attend for screening. http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(15)60123-4/abstract

Kurtosis

I think because cancer is generally considered by people to be such a frightening diagnosis, most of the public automatically assume screening=good and as illustrated by echo beach, this is propagated by the information provided by health agencies.

With regards to ending screening programmes, I think the crux of the matter is what level of overdetection most patients would find acceptable when fully informed of the benefits and harms of screening. This study looked at the issue and to me it looks like the rates of overdetections accepts are very high. Taking this at face value most people would be satisified with the actual levels of overdiagnosis, but it may also indicate that it is difficult to convey and for people to consider information about cancer risks. This probably calls for more work on how to communicate such info to aid patients come to a decision on whether to take part in screening.

The whole area of overdiagnosis/overtreatment is fascinating. It's great to see these issues gettings some attention and the Less Is More and Too Much Medicine series in JAMA Internal Medicine and the BMJ usually throw up some interesting studies.

echo beach

Thanks for that. It does show a high acceptance of over-detection, which is understandable. Free text comments like 'it is better to save one life' show the importance we put on every life (especially if it might be our own). What doesn't seem to be understood is that there are always trade-offs and, in a system where resources are finite, the lives saved by screening cost lives somewhere else.
Channel 4 ran a series on thE NHS called £2 biilion a week and counting http://www.channel4.com/programmes/nhs-2-billion-a-week-counting looking at the dilemma of where the money should be spent but naturally didn't come up with the answers.

What did surprise me in that study was that there was quite a high acceptance of the total population of 1000 being over-detected and treated in order to save 1 - 5 lives (7.1% to 13.9% of respondents accepted that scenario). The logical conclusion of that is that we don't need to screen at all but should treat everybody for cancers they might have.

Xeyn

Not sure if you can call it propaganda. What possible political gain could be intended or achieved since these screening programs cost the government money and over detection costs even more?

jumpguy

Xeyn wrote: »

Not sure if you can call it propaganda. What possible political gain could be intended or achieved since these screening programs cost the government money and over detection costs even more?

There's quite a few people heavily invested into setting up and forwarding breast cancer screening who want to believe it does good. Many doctors and scientists have given it years of work. There's a lot of very understandable human bias there - nobody wants to say "yeah, what I've been advocating for most of my career was probably a bad idea."

Changing attitudes acquired from personal experience with scientific evidence is often a struggle, for obvious reasons. A memory of using something that you felt of benefit and has an obvious, intuitive mechanism of action is a lot more compelling than a forest plot.

Governments don't want to come out and announce they're cancelling breast cancer screening, I reckon most of the general public would see it as another draconian economically motived cutback.

Interesting news article in the BMJ today on the WHO's positive report for breast cancer screening (sorry to those who can't access the BMJ article, if you have a subscription through a university or hospital you can usually access it that way). Many are not too happy with the lack of clarity in how the expert panel was chosen. Disappointingly poor scientific conduct - I'd say mammography screening has many more years left in it!

I agree with the overdiagnosis/overtreatment being a fascinating topic, and some of the results are wonderfully controversial. I think massive waiting lists confound the problem of overtreatment in Ireland - I know consultants who feel they're doing a disservice to not do unnecessary diagnostic tests for their patients because they've probably been waiting for years for their appointment. Inefficiency breeds inefficiency!

Xeyn

Propaganda is by definition a governmental proposal to influence opinion. Your view that people have something to gain is based on an assumption that individual pride is a motivating factor. That has nothing to do with irish governmental policy on breast care screening. If scrapping screening was scientific consensus (which it currently is not but maybe soon or in the future) there is no reasonable reason for the government to continue on as it would free up a lot of resources and it can be easily explained to the public. The idea that the irish government would act otherwise (especially when money is involved) in fear of possible adverse public opinion is simply not bourne out in previous acts. It borders on conspiracy theory. Please could you also cite your references for saying that 'this sort of thing is common in healthcare'
Healthcare is extremely fluid and though I've witnessed stubborn resistance most people I have worked with in a few countries now, are happy to bend with scientific consensus. Not changing practice at the drop of a hat at the start of controversy is hardly the same thing.

jumpguy

Xeyn wrote: »

Propaganda is by definition a governmental proposal to influence opinion. Your view that people have something to gain is based on an assumption that individual pride is a motivating factor. That has nothing to do with irish governmental policy on breast care screening. If scrapping screening was scientific consensus (which it currently is not but maybe soon or in the future) there is no reasonable reason for the government to continue on as it would free up a lot of resources and it can be easily explained to the public. The idea that the irish government would act otherwise (especially when money is involved) in fear of possible adverse public opinion is simply not bourne out in previous acts. It borders on conspiracy theory. Please could you also cite your references for saying that 'this sort of thing is common in healthcare'
Healthcare is extremely fluid and though I've witnessed stubborn resistance most people I have worked with in a few countries now, are happy to bend with scientific consensus. Not changing practice at the drop of a hat at the start of controversy is hardly the same thing.

Hmm, I think you're taking me up wrong. I never suggested anyone was spreading propaganda. I'm sceptical that scrapping breast cancer screening could be quite so easily explained and I think the reasons behind this are at least partly why nothing on the current controversy around its benefits vs harms hasn't made it into patient literature.

I think it's a bit much to say that scepticism regarding the political ramifications and motivations behind cancelling breast cancer screening borders anywhere near conspiracy theory. I think a similar situation exists with other aspects of Irish healthcare such as implementing the Hanley report (however, don't question me on the scientific validity of the Hanley report, I know what it suggests but not the research behind it!)

You are dead right - I shouldn't have said "this sort of thing is common in healthcare", it's just common in my experience with healthcare providers at the centres I've been at. Apologies for that.

I don't think the scientific consensus is there to propose scrapping screening yet. I don't know if it ever will tbh, since there will always be the question of how much overdiagnosis is acceptable, and for a topic so emotive I think the answer could be "quite a lot". This controversy has been going on a couple of years ago. Who decides how much overdiagnosis is acceptable and how long should it take?

echo beach

jumpguy wrote: »

I don't think the scientific consensus is there to propose scrapping screening yet. I don't know if it ever will tbh, since there will always be the question of how much overdiagnosis is acceptable, and for a topic so emotive I think the answer could be "quite a lot".

I agree that there is no reason to suggest scrapping the screening programme. Many women will happily accept the risk of over-diagnosis. What isn't acceptable is that women are being invited for screening and are hearing ads promoting it but aren't being told that there are risks and allowed to decide if they wish to accept those risks or not.
While I wouldn't use the word 'propaganda' I would say that telling only half the story isn't being completely honest or, to use a favourite word at the moment, 'transparent'.