Myths in medicine, but does their rebuttal make it possible to install the facts in a lasting way?

Cécile Bour, MD, May 24, 2020

During the Covid-19 pandemic that we have just experienced, science based on facts has been severely mistreated... General panic, mediocrity of the media combined with incredible assurance of a single researcher sounded the death knell of the serene search for facts, proclaimed as miraculous a treatment without having the proof, stepped on the principle of primum non nocere, (first do no harm), which is the foundation of our medical practice.

Independently of fundamental questions, which is not our subject, we can see that the urgency of a health situation facilitates drifts, sloppy studies, but also statements made by personalities who are not aware of scientific constraints, but who want to impose their convictions.

The interesting question is: does even strong evidence that can bury doubts and polemics have the power to put an end to myths and beliefs that are deeply rooted in medicine?

And above all, will they be tolerated in a context of serious illnesses, where public is asking for hope and where  scientific community and public authorities prefer to persist in a benevolent ideology, however fallacious?

Parallel of the epidemic situation with the myths conveyed during screening campaigns

Being a group focused on issues of public medical information and interference of non-medical stakeholders in scientific controversies, as we regularly experience during pro-cancer screening campaigns, we can draw parallels with history of breast cancer screening, where economic stakes and beliefs have prevailed over reasoning.

The public does not like uncertainty, and the tremendous desire to overcome major health threats enables the appearance and immoderate expression of promises of salvation and healing.

How was it possible to impose the mantra that screening is a preventive act, and that regular mammograms can drastically reduce the risk of dying from this disease?

To understand, a bit of history

At the very beginning of the history of screening, between the 1970s and 1980s and in various cities, counties and countries (Norway, Denmark, Canada, New York, Swedish counties, Malmö in Sweden,) women were included in so-called trials, meaning studies that consisted of simply comparing the outcome of screened women against that of unscreened women.

At that time this could be done, as women had never received an X-ray of their breasts before; they were what can be called "pure cohorts". And these early comparative studies claimed a tremendous decrease in mortality through screening, up to 30% reduction in the risk of dying from breast cancer.

 Presented in this way, this performance seemed very pleasing. In view of these results, it seemed intuitively obvious that breast cancer screening would allow earlier diagnosis, earlier treatment and thus a drastic reduction in mortality by eradicating the most serious forms.

But science is sometimes a colossus with feet of clay, and while some erected convenient convictions, other researchers, more scrupulous and suspicious, drove the stings of doubt into this base of certainties.

Indeed, it became quickly clear, (this is no longer contested by the scientific community), that these first trials had many biases, such as irregularities in method, in distribution of women between the two groups and in statistical analyses. The methodology of trials did not meet current quality criteria. For example, some of women "screened" by mammography had tumors that were already clinically palpable! Even the published results of the so-called trial in the two Swedish counties were incompatible with the data in the Swedish national file. The best results had been obtained with the less good mammograms, none of the equipment used then would be approved for use today.

While victorious publications multiply between 1992 and 2000, along with an important media and social relay on women, physicians and governments, Gotsche and Olsen, two independent Nordic researchers, proceed, in 2000-2001, to a meta-analysis according to the methodology of the independent Cochrane collective to which they belong.

And then it's a shock.

(Meta-analysis is a scientific method of combining the results of a series of studies on a given problem according to a reproducible protocol, here: does screening reduce mortality from disease. It allows a more precise analysis of the data by increasing the number of cases studied in order to draw a general conclusion. By grouping together the previous trials carried out, data on 800,000 women were obtained).

Gotsche and Olsen quickly realized that none of conducted trials were of high quality and that they all had biases, sometimes significant. By combining the best trials (the so-called Malmö 1, and the Canada 1 and 2 trials), it appears that there is no statistically significant difference in mortality between screened and unscreened women. Obviously, this is a colossal turnaround while enthusiasm for this public health procedure, which was supposed to solve the cancer problem once and for all, was in full swing.

Unfortunately for the researchers, they did not get authorization to publish their results in Cochrane reviews, and the powerful Cochrane "breast cancer group" forced them to include even biased trials in order to improve the results; after long negotiations, and with inclusion of the poorest trials, the authors still found only a very meagre and hypothetical benefit. They added at the end of their publication that the best trials show no decrease in mortality, and that the indicator "mortality from breast cancer" is unreliable.

About these negotiations that took place, read here : Trouble in the world of evidence

But in the end, the press preferred to retain the beautiful story of a life-saving screening, as did savant societies, women largely influenced by a glowing press, doctors, health authorities....[1]

However, other meta-analyses, the American USPTTF* in 2000 and the French independent review Prescrire in 2006 corroborate these equally disappointing results, even with different age groups studied, different observation periods and different cohorts.

* U.S. Prevention Services Working Group of primary care and prevention experts who review evidence of effectiveness to develop recommendations in the area of prevention.

The conflicts of interest that have plagued the whole history of breast cancer screening are very well documented on the Formindep website [2] [3], and are reported in the very complete report of the citizens' consultation (starting on page 63).


Science applies a method of doubt to beliefs and superstitions, and to itself as well, in well-done studies.

Uncertainty in the face of health dangers encourages beliefs and reassuring hopes, all the more so as this uncertainty is strong, not only on the magnitude of the threat itself, but also on the means of countering it.

The first bearer of good news becomes a hero, a savior. Any reasonable protester who applies his method of doubt becomes a public enemy.

With the history of screening we see how myths and intuitive ideas, simple to understand but false, once established, have a long way to go.

For three decades now, the myth of "preventive" screening, "life-saving for women", has been firmly anchored in people's minds, regularly promoted by the public authorities, the National Cancer Institute and the health authorities, valorized by public personalities who are committed to its promotion. Evidence of its ineffectiveness and, worse, of its deleterious effects, is little mediatized, has no right to be quoted; those who want to evoke it and warn women are called conspirators, incompetents, evildoers for the cause of women and are inaudible during the pink October campaigns.

Current Covid-19 crisis has revealed the fragility of science in relation to belief, and has highlighted all the possible excesses once we move away from the search for facts, act in haste, and adhere to convictions justified solely by their comforting character.


1] All of this is documented in the report of the citizen and scientific consultation on screening in 2016, starting on page 51, see also

As well as in Bernard Duperray book "Dépistage du cancer du sein, la grande illusion" published by Th Souccar, starting on page 26.