Evaluation of the breast cancer mortality in the German mammography-screening-program: main study - 2nd part


The Mammography Screening Program (MSP) has been introduced nationwide in Germany since 2009. Following the introduction of the program, various options for investigating the effectiveness of this program in reducing breast cancer mortality were explored as part of the program's regulatory mandate. In this context, the project ZEBRA-HS-II is conducted.
Most of the analyses of the ZEBRA-HS-II project at BIPS will be conducted as a cohort study on the basis of so-called secondary data (i. e., the data were collected in a different context and will be used 'secondarily' for this project). The data maintained at BIPS comprising a Germany-wide sample of pseudonymized insured persons from the statutory health insurance (SHI) will play a central role. In the already completed feasibility phase of this project (see Mach I and Mach II), our institute was able to demonstrate the basic suitability of these data for the planned analyses. In the first part of the main phase of the project (ZEBRA-HS-I), the data basis and the methods of analysis were developed for the analyses planned in the second part of the main study, which is currently in progress, comparing breast cancer mortality in MSP participants and non-participants. As the endpoint under consideration in this study (breast cancer mortality) is a relatively rare event, a very large study population must be included for an accurate estimate of a potential effect of MSP. In addition, an effect of the MSP would not be measurable at the population level until approximately 6–10 years after screening participation, requiring a long follow-up of the study population.
It is a particular challenge for the analyses to account for the fact that women who participate in screening are likely to differ from non-participants in terms of risk factors, among other things. Any resulting selection bias must therefore be considered in the statistical analyses. An appropriate study protocol capable of adequately accounting for these aspects has been developed in ZEBRA-HS-I.
In the current project phase ZEBRA-HS-II, BIPS is primarily working on the following tasks:
• Implementation of the analyses planned in the study protocol
• Operationalization of an emulated-target-trial-approach for the analysis on the basis of the created SHI-database
• Implementation of the analyses on breast cancer mortality and coordination of these analyses with cooperation partners in the project
• Evaluation of the results
For the analyses, the data years 2004 to 2018 and pseudonymized data from five SHI insurance providers are included. The cause of death missing in the SHI data will be added on the one hand by linkage to data from cancer registries and on the other hand by using an algorithm based on SHI data. An emulated-target-trial approach will be used to control for selection bias in the statistical analyses

Funding period

Begin:   December 2021
End:   September 2024


  • Federal Office for Radiation Protection


Dr. rer. nat. Ingo Langner

Project management (national)

Dr. Heike Minnerup, Institut für Epidemiologie und Sozialmedizin, Westfälische Wilhelms-Universität Münster