In 2021, the Belgian Cancer Registry (BCR) conducted a study to investigate the effect of participation in the Vlaams Bevolkingsonderzoek Borstkanker (Flemish Breast Cancer Screening Programme) on breast cancer-specific mortality, and the relevance and feasibility of an observational study with an endpoint of overall mortality. The research was commissioned by the Flemish government in collaboration with the Centrum voor Kankeropsporing (CvKO) (Flemish Centre for Cancer Screening), the health insurance organisations and a number of international experts.
The Flemish Government launched the Bevolkingsonderzoek Borstkanker in 2001. Since then, it has been evaluated using various structure and process indicators (Goossens et al., 2019). However, the impact of participation on hard endpoints such as mortality has not yet been investigated. For this, breast cancer-specific mortality is the most commonly used outcome measure and also the one for which the greatest effect is expected. However, some experts feel that this endpoint only allows an incomplete evaluation of the potential benefits and harms of screening. They therefore recommend that, when assessing a population screening programme, the effect on overall mortality should also be examined.
To measure the effect of participation in the Vlaams Bevolkingsonderzoek Borstkanker (Flemish Breast Cancer Screening Programme) on breast cancer-specific mortality, an observational case-referent study was conducted based on data from the screening programme supplemented with available administrative data obtained from the Agence InterMutualiste (AIM) (the agency responsible for collating data from Belgium’s seven health insurance funds) such as cause-specific mortality rates and cancer registration data. Of all women who were in the population screening target group from 2005 to 2012, those who died of breast cancer between 2005 and 2017 and were eligible for screening before their diagnosis were taken as cases. For each case, four women from the same population were used as referents. Analyses of the association between breast cancer-specific mortality and participation in population screening were adjusted for possible influencing factors (socioeconomic status, year of diagnosis, and age).
A thorough literature review was conducted on the effect of participation on overall mortality, and consultations were held with international experts. In addition, the feasibility was investigated of an observational study with excess mortality and/or causes of death other than breast cancer as outcome measures. However, due in part to methodological obstacles, the conclusion was reached that an analysis of the association between participation and overall mortality could not be made.
The results of this project were reported to the Flemish Government and presented to the Flemish working group on Bevolkingsonderzoek Borstkanker (Breast Cancer Screening). Results concerning the effect of participation on breast cancer-specific mortality were published in a scientific journal.
Source:
Goossens, M., De Brabander, I., & Kellen, E. (2019). Flemish breast cancer screening programme: 15 years of key performance indicators (2002-2016). BMC Cancer, 19(1):1012. https://doi.org/10.1186/s12885-019-6230-z.
