Tag Archives: Breast cancer

Breast Screening – The Truth…

21 Replies

I am against over-medicalisation in all its forms. So, apart from being very skeptical about preventative medicine in the area of heart disease, I also worry about other forms of preventative medicine. Breast cancer screening is one area where the balance between benefit and harm may well slip towards harm. Yet, it is presented as an absolute good.

One man who is very critical of breast cancer screening  is Professor Peter Gotzsche, who is the clinical director fo the Nordic Cochrane Collaboration Centre, and has written a book called ‘Mammography Screening. Truth, lies and controversy.’ He outlines exactly what has been going on in this are, and makes it very clear that there are significant problems. Primarily with overdiagnosis (there are other problems, but no time for everything in one blog).

Overdiagnosis means finding ‘lumps’ of other suspcious things on mammography ‘lumps’ that would never have caused any problem.  How big is this problem. Well,  detailed pathological studies done in Australia found that in women who had died of other thngs (not breast cancer) had the following pathologies, any of which could lead to a ‘diagnosis’ of breast cancer if found on a biopsy :

Hyperplasia 12.6%
Carcinoma in situe 13%
Focal secretory changes 24.1%
Perilobular hemangioma 11.2%
Radial scars
(precursor of infiltrating ductal cancer)		 7.7%

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1977023/?page=1

In other words, a very high percentage of women have ‘cancerous’ lesions in their breasts. Yet, around 4% of women die of breast cancer.  In the words of the authors of this study…

‘….in any case, the high frequency of ductal hyperplasia and CIS (carcinoma in situ) 25.6% suggests that only a small proportion of these must ever progress to invasive carcinoma.’

If only a small proportion of ‘cancerous’ lesion actually progress to invasive carcinoma, then the majority of those found would never cause any harm to the woman. Thus overdiagnosis must be a very major problem indeed. Ironically, the more detailed an accurate screening beomces, the more overdiagnosis will occur.

Anyway, I was unsurprised to see the recent headline:

‘Breast cancer screening does ‘more good than harm’ http://www.bbc.co.uk/news/health-19571173

‘Breast cancer screening saves the lives of two women for every one patient who receives unnecessary treatment, according to a major European review. There has been a fierce debate about the use of screening, and policy is being reviewed in England.

The latest study, published in the Journal of Medical Screening, said at least seven lives were saved for every 1,000 women screened. Health charities say the findings will provide further clarity for women. Tens of thousands of women die from breast cancer across Europe each year. The effectiveness of screening programmes across the continent was evaluated in a series of studies.

It concluded that for every 1,000 women screened, between seven and nine lives were saved and four cases were over-diagnosed.. Mammograms spot dangerous tumours, increasing the chances of survival, but also detect lumps that are essentially harmless, exposing some women to undue anxiety and surgery.

Screening doesn’t just save lives today or tomorrow, it saves lives 10-20 years down the line” Prof Stephen Duffy Queen Mary, University of London.’

I know that there is no possible way that anyone can know that for every seven and nine lives ‘saved’ four cases were overdiagnosed. This is scientific nonsense. The reality is that more cases must have been overdiagnosed than future invasive cancers diagnosed.

I have asked someone to forward me the full studies on which this BBC story was based.  I have only one part of it so far, and it is a part that worries me greatly, for it makes the following statement.

‘What these papers tell us is that the time has come to move away from relying solely on the older randomized trials of mammographic screening for the evidence-base, and to use data regularly collected and monitored from service screening programmes, with proper statistical analyses in addition to the results from the randomized trials. The authors of these articles set a precedent for how this could be done effectively.’ http://xa.yimg.com/kq/groups/14947167/193204470/name/benefits%20and%20%20harms%20of%20mammograms%202012.pdf

The time has come to move away from relying on randomized trials!

Once you move away from randomized trials you are no longer doing science. You are doing dogma. At which point the truth can never, ever, be obtained. When someone tells me we should use data regularly collected and monitored from service screening programmes with ‘proper’ statistical analysis – I know that THE TRUTH is being buried.

So long science.

 

Prevention is better than cure – maybe

11 Replies

[Part one- of many – probably]

The last few decades have seen medicine move inexorably towards the idea that its primary function is to prevent diseases from happening in the first place. Rather than trying to cure them after they have started. Which is a nice simple thought. It also seems an inarguably good thing. So presenting any case against preventative medicine can seem wilfully contrarian, and is often met with extreme anger….’do you want people to die!’

In truth, I do not want people to die – although I would have to add that we are all going to die anyway, whatever we do, so what would be your point exactly? No, what I want is for more people to understand that prevention is not a panacea. It can do more harm than good. Indeed, in certain cases, it can cause significant damage to health and general wellbeing.

It almost goes without saying that many preventative activities are a good thing. Clean water supply, surgeons washing their hands before operations, stopping smoking, taking exercise, and suchlike. But once you have got past such obviously useful activities, the benefit to harm ratio can rapidly become far less straightforward.

I spent some time recently reading a book by Peter Gotzsche called ‘Mammography Screening, Truth Lies and Controversy’. It helped to highlight many issues about cancer screening that have disturbed me for some time.

The first, and most important, is this. Many women have cancerous cells in their breasts. Around 40% of women in their forties, on autopsy, have detectable breast cancer(s). To balance this out, most men after forty, if you took out their prostate and sliced them open, would have detectable cancer cells present as well.

Although 40% of women have potentially detectable cancers, around 4% of women die of breast cancer.

This means that, the vast majority of breast cancers do not actually do anything very much. They sit there, and they sit there and…..presumably, many of them regress (shrink) back down to nothing at all. They cause no health problems, and a large proportion of women will die with, rather than of, breast cancer.

Increasingly, however, someone calls you in for mammography, and you have your scan, and they find a small suspicious lump. In an instant you turn from a happy healthy person, into someone with cancer – the deadly killer. At which point all hell breaks loose.

Now, if that cancer happened to be one that was going to grow and kill you, then all the crushing fear and despair, and biopsies, and operations, would be a small price to pay. But if that cancer was one of the 90% that was going to sit there doing nothing for the rest of your life, then you have paid an exceedingly heavy price indeed.

In addition to this downside, in many cases, the suspicious lump was not even cancerous at all. The mammography identified a possible cancer – and it wasn’t. In screening terms this is known as the false positive. In human terms it is known as, the most terrifying thing that has ever happened to me….. and you’re telling me it was a mistake!

There are those who take an absolutist position on this and say that ‘If even one life is saved, it is all worth it.’ Perhaps, but mammography exposes a women to a radiation dose that is around five hundred times that of a simple chest x-ray. Some estimates suggest that each mammography carries a one in two thousand risk of causing cancer.

If, over a lifetime of screening, you have ten mammograms, that represents  a one in two hundred chance that a procedure designed to pick up cancer, may actually cause it. Or maybe the risk is greater than is. Is the potential to cause cancer additive, or multiplicative? I can find no-one able to answer this particular question.

Then, of course, there is the risk that the mammogram is negative. You are reassured that you do not have cancer – but you do. So when you feel a lump you think. It’s OK, I’ve had a mammogram and I am clear. But you are not. You could have been treated, but you waited too long. This is known as the false negative.

I could go on into further downsides, but I hope to have made the general issue clear. Breast cancer screening sounds wonderful, it is presented as an absolute good, but it is not. There are significant. and not uncommon. harms. Yet such is the zealotry (I hesitated to use the word zealotry, but I can’t think of a better one) of those involved in breast cancer screening that no downsides at all are ever presented.

Screening is good, breast cancer screening is perfect….or not. Here is what Professor Michael Baum has to say on the matter:

‘After a systematic review of all websites on this subject, a recent paper in the British Medical Journal concluded that women are being coerced into screening by those organisations connected to the government or the screening industry. I am neither for nor against screening, but I am a passionate champion of informed choice for women. For an informed choice women should be treated as adults and provided with balanced information, not with propaganda.’ http://www.spiked-online.com/articles/0000000CA382.htm

Preventative medicine, and screening and scanning, has almost become a religion for those involved. Only the positives are ever mentioned, and those who dare criticise are subjected to ruthless attacks. As I will be for writing this.

Prevention is better than cure?

Sometimes. Maybe.