This graphic is based on the Cochrane meta-analysis and M. Baum's study on the consequences of screening when treatment effects are considered.
The Cochrane Collaboration (currently the Cochrane Organization) is a non-profit organization composed of volunteer researchers from all over the world who are financially independent of the pharmaceutical industry.
This collaboration aims to systematically organize scientific information and medical research data based on properly conducted clinical trials. The scientifically validated data are summarized in an accessible way and published in the Cochrane library.
To assess the screening results and weigh the benefits and risks, researchers gathered data from all previous screening studies, which included 600,000 women – both screened and not screened. They combined the findings of all studies conducted since the 1970s to compare the benefits and harms of each situation. To make their results more concrete, they projected them onto two fictitious populations of 2 000 women in the form of a "dot chart."
Each dot represents a woman. Researchers from the Cochrane Collaboration indicate overdiagnosis (red dots), false alarms (blue dots), avoidable deaths (dark dots), and deaths (black dots) to provide a comparative picture of what happens when you have a screening versus when you don't.
Their calculations are summarized here. https://www.cochrane.org/CD001877/BREASTCA_screening-for-breast-cancer-with-mammography
English brochure is here: https://www.cochrane.dk/screening-breast-cancer-mammography
Study of Professor Michael Baum, BMJ 2013
We incorporated the results of M.Baum's study, published in the BMJ journal in 2013.
Michael Baum is an Emeritus Professor of Surgery, Division of Surgery and Interventional sciences, University College London, London WC1E 6BT, United Kingdom.
According to this researcher, when treatment-related deaths are included in the mortality count, the harms of breast cancer screening outweigh the benefits.
These deaths must be considered because the expected benefit of screening (the golden dot materializing the 'life saved') is outweighed by the death due to therapeutic complications (the green dot materializing the 'life shortened' by damage caused by surgery, radiotherapy, chemotherapy, and hormone therapy).
Quote from the last paragraph of the study:
"If each of those were translated into total lives saved from all causes then I would remain content but, unfortunately, when 10 000 are screened along the way about 120 to 140 cases will be overdiagnosed with the current age group invited. Four fifths of these women would receive radiotherapy and would be at an increased risk of dying of ischaemic heart disease and lung cancer. Knowing the background risks (box 2) and multiplying these by the factors 1.27 and 1.78 gives us increases of 2% for lung cancer and 1.33% for myocardial infarction. Adding that to all cause mortality rates I crudely estimate that an additional one to three deaths might be expected from other causes for every breast cancer death avoided."