What are the implications of the breast cancer study reported below by Associate Professor Alex Barratt?
Croakey has asked a range of individuals and groups to respond, and will post their comments as they land.
Sally Crossing, AM, Chair of Cancer Voices NSW, and member of the Breast Cancer Action Group NSW, comments:
“I was almost at a loss on how to respond to the latest study about the downsides of breast mammography screening. So I asked an informal – lets ‘fess up – quite impromptu group of women of the screening age what they thought. Five were “well’ women of the target age group, who screened happily and regularly, two others had been diagnosed – one detected early with no further disease, the other not so lucky.
This large sample, to a women, expressed concern about the findings of Morrell et al which have given rise to much media speculation and consequent public concern. Where does this leave us now?, they asked.
Discussion continued with the fairly quick result that none of those still screening would stop because – and here’s the rub – we have absolutely no way of knowing whether our little early detected invasive tumour is a “goodie’ or a baddie’. Not one of those women wanted to take such a risk and could not imagine anyone wittingly doing so. The two women who had had breast cancer diagnoses had both been detected early – one was fine, and the other not.
The “downsiders” also refer to the “harms” of breast screening. I know those of us who are breast cancer survivors may be called biased, but we feel pretty comfortable that the “harms” of having to wait for results, perhaps having a fine needle biopsy, even a small excision – are not very major in the big picture of knowing whether you have cancer or not.
Of course, having chemotherapy is a big “harm’ – and this is where it is so important for the research community to find out how to tell if one small lump needs full bore treatment, or not. There are shades and degrees in this discussion that were not in the ambit of the downsiders.
I notice the journal article is mainly interested in outcomes as measured by death rates. Here’s another thing to consider – we women are mainly interested in living as long and as well as possible. We would like to see the endpoint being years of quality life, not numbers of deaths. And thanks to early detection and more personalised and less toxic treatments, many of us are living much longer and better with our disease.
Of course people should be given good information about any possible risks and benefits of any medical intervention, and indeed of tests like screening. It needs to be very well accepted information, expressed in terms that are completely understandable. I don’t think we have reached that point with these findings.
Cancer consumer advocates are concerned that studies on possible over-diagnosis due to screening may be used to restrict publicly-funded screening and undermine the message that early detection saves lives.
Could we not direct the research money which supports these studies to the elephant in the room – finding out which detected cancers will progress and which won’t? Suspicion of over-diagnosis then would not be a researchable issue.
Professor Ian Olver, Chief Executive Officer Cancer Council Australia, writes:
“Breast screening has been estimated to reduce mortality from breast cancer in the target population of 50 to 69 year old women by up to 35%.
One of the downsides, though is that the screening test is far from perfect and can result in overdiagnosis. There are widely ranging estimates in the literature about the extent of overdiagnosis because population modelling includes the need to make assumptions which introduces variability.
However, there is no doubt that overdiagnosis does occur, against which the decrease in death has to be balanced.Individual women need to be informed about this.
Having said that, at the individual level we cannot distinguish which of the invasive cancers diagnosed at screening will have an indolent course and need not be treated.
The first consequence of overdiagnosis is that it points out the necessity for further research into being able to detect the slow growing from the more aggressive cancers so that we can identify a group that does not need treatment.
Until that occurs, women will be advised to have treatment which could save their lives.
The participation rate in breast screening is still not ideal and women are still encouraged to have a screening mammogram in the target age group to decrease breast cancer mortality as far as possible.
It would be counterproductive if women were dissuaded from participating in what has been a successful screening program simply because overdiagnosis occurs.”
Terry Slevin, Cancer Council WA, writes:
“The Sydney University study is important in helping us understand better the impact of breast cancer screening – but for many of us there are few surprises. They quantify an effect we’ve known about for some time that applies to all cancer screening – not just breast cancer.
But as the resources are more available for breast cancer than most other areas of cancer – we tend to get better data earlier on breast cancer issue compared to other forms of the disease.
In simple terms – when we go systematically looking for more cancer – we are pretty much bound to find it. It has certainly happened in prostate cancer and is likely to happen in bowel cancer with the National – albeit somewhat half baked – Bowel Cancer Screening program, where not nearly enough people are invited to participate compared to the number we believe will benefit.
The question is – can we maximise the benefit of finding more cancer early so that the “price” of finding and unnecessarily treating cancers that would have otherwise cause no harm, is justified.
And Alex Barratt is right.
Yes – we need to come up with better, more accurate tests that more precisely discriminate between the cancers that need intervention and treatment and those that can be safely left alone. And we need to better inform those invited to screening of the benefits AND the risks.
Key to this is advancing technologies and ensuring those are thoroughly evaluated before they are marketed. Easier said than done when many in the biotech world see the next big cancer test is the holy grail for company profits.
Another way to swing the odds in our favour is being VERY careful who we capture in the screening net, and ensuring that everyone is very clear about what they are letting themselves in for.
And all of that is achieved if we keep talking about these issues based on the highest quality research which must be communicated in a clear and accessible manner.
We need to continually weigh up what benefits we get from cancer screening and what price we pay for those benefits.
These principles apply to breast cancer screening, bowel cancer screening and the testing that is done for prostate cancer. It is important to understand that, based on the best available evidence, most health and medical experts who I deal with agree that the benefits substantially outweigh the costs for breast and bowel cancer screening, but that case has not been proven for prostate cancer screening.
But a nice way to think about it is from a punter’s point if view.
Image you had a cancer (of the x) test today. The test is positive. You then undergo further examination and the presence of cancer is confirmed. You undergo treatment. Probably surgery, radiotherapy and chemotherapy – and all that goes with them.
In 2019, you are sitting in your comfy lounge chair at home and someone tells you that you had a one in 50 chance of having had your life saved through having had your test. And a 49 in 50 chance of having undergone all that unnecessarily. What would you think? Those are the numbers for prostate cancer.
What if it was one in 10 for having saved your life versus 9 in 10 being unnecessary?
Or one in 3 verses 2 in 3 ?
Where is the cut point for regret ?
Now come back to today. What numbers from the above scenario would influence whether you do or don’t do the test. And you are scheduled to do the test tomorrow….
Tough huh ! But those are the challenges we face – and a big part of that is how we better communicate that story to the people we ask to make that decision. The people we invite to be screened.”
Sue Lockwood, Breast Cancer Action Group Vic, writes:
Alex Barratt has been pushing the need for better information and decision aids for women undergoing screening for years. Of course she is right, we do need to make sure that women are properly informed. But papers such as the one she has just published giving figures for the “overdiagnosis” of breast cancer do not help inform women.
This is a straight epidemiological study which has no relevance to decisions made by individual women. A radiologist looking at a mammogram cannot tell whether the invasive cancer he or she can see is one which will develop into full blown cancer or not. The surgeon who removes the lump and the pathologist who dissects it cannot distinguish one lump from another except in broad brush terms, e.g. oestrogen receptor positive or not, Her2 positive or not and the like. Similarly the oncologist has no real information except for the examples mentioned above. The chemotherapy women respond to is a bit like picking the winner in the Melbourne Cup. The main difference is that you can keep trying different horses on different courses.
The other major flaw in Barratt’s argument relates to harms. She sees unnecessary treatment, surgery, radiotherapy, chemotherapy , and the psychological trauma of a diagnosis of breast cancer as a harm. Of course she is right, the treatment of breast cancer can be a harm if your breast cancer is not going to progress. But as I have argued it is impossible at the moment to determine which women are being harmed and which women are getting the correct treatment.. Most women, although they find the treatment traumatic, would see it as taking the opportunity to do as much as possible to rid their body of breast cancer.
I have argued for many years that the greatest harm is one where breast cancer is not diagnosed correctly or in a timely fashion. This can lead to the greatest harm of all, DEATH. This is obviously a disaster for the woman, but also for her family. It is a trauma several orders of magnitude bigger than the trauma of initial treatment for breast cancer.
This research should never have been funded. It is a complete waste of precious funds. It has not provided any information we did not know already. Perhaps it made the data available more accurate, but is provides absolutely no information to inform women or to help improve treatment outcomes.
We already deceive women by providing only 5 year survival statistics. These figures give a biased view of survival as we know that women continue to die of breast cancer over the long term, 10, 20 years after their initial diagnosis. We would be much better off looking at how women survive their breast cancers, how many actually go on the develop advanced breast cancer, how long they live and how well they live with advanced disease.
Please let us focus on the important research, which provides the opportunity to improve the lives of women with breast cancer.