The ethics have been questioned of running new randomized controlled trials to determine the benefits and possible harms of population screening for breast cancer (see As an ethics representative on the Swiss Medical Board, I believe that there is a moral requirement for this type of study. We need to ascertain whether advances in treatment have cancelled out the benefits of early diagnosis through screening.

The random allocation of women into groups that have mammograms with different detection thresholds (see H. G. Welch The New York Times 29 December 2013; or no mammogram would be ethically problematic if we knew that screening provided a significant net benefit. But this has not been established.

I contend that most women would prefer to participate in a trial that helps to clarify the benefit of screening, rather than continuing to be subjected to screening of doubtful benefit and with potential for significant harm through overdiagnosis.