Today’s title is from the Daily Mail: “The expert branded a woman hater for saying breast cancer screening ruins lives.”
What could be more sensible than having a mammogram?
If a tiny tumour is growing in your breast, you want to find it as soon as possible and treat it before it has a chance to spread and become life-threatening
That is the reasoning used by most women. But it doesn’t satisfy Peter Gotzsche, a Danish physician with statistical sympathies, and author of the “controversial” book Mammography Screening: Truth, Lies and Controversy.
The standard reasons given for young, healthy, asymptomatic women to receive breast cancer screening don’t satisfy yours truly, either. I wrote about this in the Decision Calculator and
in the peer-reviewed (which guarantees its accuracy, right?) paper “Assessing the skill of Yes/No Predictions” in Biometrics (pdf).
From Gotzsche’s book introduction:
The most effective way to decrease women’s risk of becoming a breast cancer patient is to avoid attending screening.
Mammography screening is one of the greatest controversies in healthcare, and the extent to which some scientists have sacrificed sound scientific principles in order to arrive at politically acceptable results in their research is extraordinary. In contrast, neutral observers increasingly find that the benefit has been much oversold and that the harms are much greater than previously believed.
When Gotzsche “looked at the figures produced to mark the 20th anniversary of the UK screening programme, Professor Gotzsche’s analysis suggested that for every 2,000 women screened regularly for ten years, just one will benefit from the screening.” Even worse, “At the same time, ten healthy women will, as a consequence, become cancer patients and be treated unnecessarily.”
We’d thus expect that since Gotzsche claims and has documented inefficiencies, errors, misconceptions, and the harm that can result from screenings, he has been lauded far and wide, particularly by women’s groups. Right?
Instead, as the DM reports, “for almost ten years there has been a concerted campaign to discredit him, while scanning authorities in the UK, U.S. and Europe have done little to address his criticisms.” When his first paper on the subject was published, “Experts in the screening industry expressed ‘dismay’ that it would erode public confidence in screening and urged women to ignore it.” It was said that those who recommended against screening “don’t like women.”
Another researcher, thinking of Gotzsche’s swimming against the tide of Consensus, wrote, “What is remarkable to me is that this man calls himself a scientist since he obviously, knowingly ignores the scientific method to further his own agenda. I cannot believe his [sic] is so intellectually deficient.” Now where else have we seen this kind of calm, rational discussion of scientific matters? Ah, skip it.
The DM does a good job summarizing one of the ways screening can be harmful:
But what can be wrong with checking to catch breast cancer as early as possible?
If every tumour that showed up on a mammogram eventually spread around the body, no one could object. But cancer isn’t like that.
‘It is a biological fact of life that we cannot avoid getting cancer as we get older’ says Professor Gotzsche.
‘It’s so common nearly all middle-aged people will have some sign of it and most of them will die without having had any symptoms as a result.’
In other words, scanning finds cancerous changes that would otherwise never have caused a problem in your lifetime.
But once a mammogram picks up something that might be a tumour, you’re on your way to becoming a cancer patient because there are no reliable ways of telling if you’ve got the slow-growing or disappearing type, or if it is going to become dangerously invasive.
You will be sent for a biopsy and, if it’s cancerous, you get the full cancer works — surgery, chemotherapy and radiation, and possibly have your breast removed.
Thousands who would otherwise have remained perfectly healthy — because their cancers would never have caused a problem — become cancer patients.
And there is the chance of a “false positive”, when the screening incorrectly says a woman has cancer when she does not. This leads to angst, worry, stress, possibly even tears and fretting. And to further, possibly more intrusive, screenings to verify the first.
Screenings has costs and not just benefits. Each woman needs to weigh those costs and benefits for herself and her family—and she must realize that those costs and benefits are not the same as the doctors or the women groups advocating screening.