Once ideas become accepted in health it is hard to change them. Yet knowledge presses forward and what was once thought to be the case may be shown not to be. Our understanding of cancer is evolving but the system is locked into a very 1970’s approach.
The overarching assumption with cancer is that all cancers if left alone will grow and ultimately kill the person who has it. It may take a longer or shorter time but it is inevitable. This has led to the other overarching assumption, which is that early detection is best. This has seen the growth of cancer screening programs. This approach follows the war on cancer attitude first promoted by then President Richard Nixon in 1971 with a view to eradication by 1976.
Cancer has the ability to strike fear into people and hence the notion that the finding of cancer cells may not be a one-way ticket to an early grave, is a difficult notion to wrap your head around.
However what is becoming clearer and clearer is that cancers are NOT all the same and that it is not always a one way street. It is also becoming clearer that finding cancers “too early” is not always helpful as the treatment may be worse than the condition.
Surely this cannot be true you must be thinking.
Here are some sobering figures. Around one third of autopsies on men aged 40-60 find cancer cells in the prostate. I have written previously about how PSA screening results in around 50 men having surgery for one to benefit.
As many as 30% of breast cancers, found on mammograms, would not manifest clinically in that woman’s lifetime. If they are found though, they will be treated and the belief will be, that the test saved the life. A study published in The Archives of Internal Medicine shows that most women with screening detected cancers are either diagnosed early (with no effect on the end result) or over-diagnosed, meaning that they would NOT have had a problem anyway.
Screening mammography has developed a saintly air about it and any questioning of it is quickly struck down. But what if it is not as saintly as it is presented. Don’t women have the right to know?
A long term European review found that screening mammography had not contributed to improvements in breast cancer outlook. It studied three pairs of countries where mammography had been introduced at different times (up to 15 years apart) and found the changes in breast cancer survival was the same in all countries. Part of this was due to better treatment and part is due to finding and treating cancers, which would not have developed.
Does over-diagnosis matter? Yes it does. There is considerable anxiety caused by the detection of “suspicious “ lumps and women may undergo biopsies, surgery and other treatments, which will not benefit them and may do harm. Whilst it sounds obvious the point is, who wants surgery for the sake of it?
Lets not even consider the economic cost of tests and treatments, which achieve nothing.
In the USA 39 million mammograms are done each year and it is estimated that between 4000 and 18000 women actually benefit. That is one in 2000 at best and this sits with UK figures previously published in the BMJ, which estimated one in 1622 women benefited from screening mammography.
The driving force behind screening is that early detection matters. Our capacity to detect has now exceeded our capacity to understand what we find. Concurrently treatments have improved.
So what does this mean practically? It means that it is actually worth waiting to see which cancers manifest clinically. The outlook when this happens is essentially the same as when they are picked up by screening and the chances of treating something that needs no treatment is reduced significantly.
Screening programs have been introduced as “life saving” measures but there was never any evidence that this would be the case-just reasonable (at the time) assumptions. It was never envisaged that there would be the sort of co-lateral damage we are now seeing. Furthermore screening is presented as simple and with only potential benefit. The potential harms are never discussed. People have been made to feel they are doing the “wrong thing” if they ignore screening.
It is time that a balanced picture was presented to the public. Let us hear about the potential benefits of screening tests but let us also hear about the “side effects” in the same way as these are discussed with pharmaceuticals.
Professors Robin Bell and Robert Burton wrote this useful summation in the MJA:
“… A simple message of unqualified benefit from screening is no longer appropriate.
So what should women be advised about screening mammography?
The harm of screening is not currently being explained in the UK screening program, leading to a call for a better balance in the information provided to women.
We consider that Australian women should also be given more information about the balance of benefits and harm of screening so that they are better equipped to make an informed choice.”
I believe this applies to women worldwide.