Breast cancer mortality and screening: results of a randomized trial approved by the School of Public Health, University of Toronto, Toronto, Ontario M5T 3M7, Canada;

15 Feb

In 1980 the School of Public Health, University of Toronto, Toronto, Ontario M5T 3M7, Canada approved a randomized controlled trial: 89 835 women, aged 40 to 59, were affected at random to either an annual mammogram during five years or an annual physical examination without any mammogram during the same period of time. Now 25 years after the results are publicly available here:

And they are astonishing, so astonishing that we feel compelled to quote them:

“Conclusion Annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available. Overall, 22% (106/484) of screen detected invasive breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial.”

Meaning: not only searchers did not find any evidence of difference in the instantaneous risk of death from breast cancer between the two groups (hazard ratio not significantly different from one) but moreover what they found was over-diagnosis of breast cancers (ie 106 more cancers in the mammogram group even 15 years after the screening that is even when all the cancers of the non screening group should have been detected due to their natural evolution).

Those chilling facts have to be discussed, that is the least that we should do in the health services community given the budget allocated to breast cancer screening by mammograms.

Perhaps the mammographies in the eighties were not as sophisticated as those which are offered now? And in the contrary physicians in the eighties were perhaps more efficient than the 21century doctors at the physical examination of the breast?

Thanks to the incidental economist who gave me the news:

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