1  assigned during different time periods

Acknowledgements
The scientific guarantor of this publication is Sylvia H. Heywang-Koebrunner. The authors of this manuscript declare relationships with the following companies:
Prof. Sylvia Heywang-Koebrunner:
1. I am head of the Reference Center Mammography Screening Munich which is responsible for quality assurance and training of screeners in Bavaria and Thuringia. This makes 50 % of my work.
2. I work as head of a screening unit and I work in private practice, specialized in breast imaging and interventions. About 70 % of my work is associated with mammography screening
Prof. Ingrid Schreer: No other relationships/conditions/circumstances that present a potential conflict of interest
Dr. Astrid Hacker: I'm an employee of the Reference Center for Mammography Screening Munich.
Dr. Maria Noftz: No other relationships/conditions/circumstances that present a potential conflict of interest
Prof. Dr. Alexander Katalinic: I am chair of the scientific committee of the German Mammography Screening. This is an independent scientific committee, which is giving advice for the ongoing program. The task is honorary; there is no fee paid to me or any committee member. Only costs for travel to the committee meetings are paid by the screening program.
The authors state that this work has not received any funding. One of the authors has significant statistical expertise. Institutional Review Board approval was obtained. No study subjects or cohorts have been previously reported in any other journal. Methodology: The special report is a retrospective review on an existing trial performed in the 1980s (CNBSS) and a lately published follow-up study of the CNBSS. It is performed at one institution.