Benefit and Risk of Mammography Screening – Considerations from an Epidemiological Viewpoint: Shared Decision-Making

Women would like to know what they have to gain from screening. Around the world, this question is answered with data on the number of deaths prevented per number of women screened. It thus seems strange that the authors would claim that the reference figures presented by Mühlhauser and Höldke are somehow artificial.

Women would certainly also like to know what the chance of successful treatment would be in the event that a tumor is discovered. The authors answer this question as follows: over the course of 10 years, out of 100 screened women found to have breast cancer, 20 will die instead of 31. Thus, there will be 11 fewer deaths out of 100 screened women in 10 years, or, rounding off, 1 woman saved out of 10. Who could fail to be impressed by this?

The authors' response to the question of treatment can be made still more precise once the histological findings are available, because the stage of disease determines whether the chance of survival will be greater or smaller.

The benefit of screening (not of potential later treatment) can be calculated from the article's table 1. Out of 100 000 screened women, the number who go on to die of breast cancer in the next 10 years is reduced from 155 (the figure among non-screened women) to 101, i.e., a reduction by 54/100 000 in 10 years. Rounding off, this corresponds to 1 woman saved out of 2000 in 10 years. Does anyone still want to be screened?

This discrepancy between the internationally standard manner of presentation and that chosen by Becker and Junkermann encapsulates the entire problem of the way we choose to deal with participative decision-making.

If we wish to free the concept of shared decision-making from pure political correctness, then we must tell women what individual benefit they can expect from screening, as well as what harm might come to them from it (something that the article does not completely address) – even if doing so carries with it the danger that fewer women will choose to be screened.

Society's desire for a high rate of screening, so that the maximal public health benefit can be achieved, is another matter. This desire, too, has a rationale behind it. We physicians must choose which side we prefer to stand on.
DOI: 10.3238/arztebl.2008.0420b

Prof. Dr. med. Heinz-Harald Abholz
Leiter der Abteilung für Allgemeinmedizin
Heinrich-Heine-Universität Düsseldorf
Moorenstr. 5, 40225 Düsseldorf, Germany
Abholz@med.uni-duesseldorf.de