I'm also not sure we should be contemplating abandoning screening for e.g. breast cancers because of false positives.If they find something and tell the woman there is a chance it's benign, surely it's her choice. But you need to give her the full figures.For every women that dies 3-10 are treated unnecessarily is a bit meaningless if you don't know how many that are treated would have died without treatment.
Like all of life's quandaries, where there is a benefit there is also a burden. Mitigating the risk with blanket coverage.
How about a cure for the common cold.
Nobody is advocating screening for breast cancer as it is one of the few cancer screening programs that generally shows more benefits than harm.
The main harm of any screening program is often over-diagnosis - so the levels of overdiagnosis do affect whether the benefits of the program outweigh the harm.
We do know exact figures for the level of over-diagnosis because we know how many people would die from a given type of disease without screening. The BMJ argue that women are not given enough detail about the exact level of over diagnosis and over treatment. For example, they complained that the leaflets on breast screening do not mention over-diagnosis as one of the potential negatives of screening. (I have also seen articles that most doctors give poor advice on screening as they significantly underestimate the levels of over-diagnosis.)
There have been changes for breast screening to reduce the harm caused by reducing the number of people screened to focus on the groups most likely to develop cancer e.g. those 50 and over and those with family history of breast cancer.
Below are figures from Cancer Research about breast cancer screening. In their example, screening of 1,000 women will reduce the deaths from breast cancer by 5 (from 21 to 16) and 17 women will be over-diagnosed with cancers that would not have caused them any harm. The point is that over-diagnosis is not trivial. Women can have operations, chemotherapy and radiotherapy which can cause serious side effects - which in extreme cases may even mean death for a few.
Overall though the case for breast cancer screening seems positive.
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However, looking at screening for prostate cancer the picture is much less positive. Basically it would hardly affect the rate of death but would generate a lot of false positives.
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A number of factors come into this. For example, PSA screening produces a high rate of false positives and prostate cancer is less fatal than breast cancer - around 90% of men who get prostate cancer will not die from it. So there is less potential benefit in terms of lives that you could save as most people would survive anyway. Also it can be difficult to treat without causing other side effects such as incontinence and impotence. So those over-diagnosed can suffer considerable issues.
That doesn't make sense?
So breast cancer screening is beneficial.Which you argued against.
Prostate is a bit more difficult.Although over PSA diagnosis is well recognised and explained.My FIL was diagnosed too late and it got everywhere and he died from it. My Dad was diagnosed early (both cases around 25 years ago) and has had no issues from the targetted radiotherapy that killed off the tumour cells.
Sorry for the anecdotes.
Yep it made no sense at all - I missed a word there which I have added in bold.....
I never intended to argue against breast screening. I just meant to point out that it has significant side effects and there are still discussions over the size of positives and the negatives.
I have no problem with anecdotes - it is often our only real experience of the issues that we are discussing here.
Thanks, makes complete sense now data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7