There is accumulating evidence that digital breast tomosynthesis increases the detection rate and reduces the recall rate in population-based screening for breast cancer compared to standard digital mammography.
It is not clear whether the additional cancers detected with DBT reduce the number of breast cancers detected between screening examinations (interval breast cancers). It is possible that these additional cancers could be slow-growing cancers that would never have caused symptoms and would have never been detected without participation in screening (overdiagnosis).
A project group from the University of Sydney in Australia aims to investigate this issue by combining data from studies performed in population-based screening programs for breast cancer in Norway, Sweden and Italy.
The aim of their study is to use individual-level data to examine the interval cancer rates among women screened with DBT compared to DM. Their study will also compare the rates of breast cancer detected through screening (screen-detected breast cancer) and recall associated with the two screening techniques.
Data and project organisation
BreastScreen Norway participate in the project by providing screening information from the Cancer Registry of Norway, in accordance with the Cancer Registry Regulations (kreftregisterforskriften).
The study population include about 140,000 women aged 50-69 who were screened in BreastScreen Norway in Oslo, Vestfold and Vestre Viken in 2014 and 2015, and in Bergen between 2016 and 2019. The project will only include data from women who have agreed that their personal data related to negative screening results being permanently stored at the Registry.
This study is registry-based, and the women included will not be contacted regarding the project. It will be impossible to identify individuals from any published study results.
The University of Sydney (Australia) is the principal investigator of the project, and in charge of checking, managing and analysing the collective database, as well as obtaining necessary approvals in Australia.
The Cancer Registry of Norway is a collaborator and is responsible for obtaining the necessary ethical approvals in Norway, as well as extracting, pseudonymizing and delivering data to the project.
Lund University (Sweden) and Azienda Provincale Servizi Sanitari (Italy) are also project collaborators. They are responsible for obtaining necessary ethical approvals and delivering data from studies performed in their countries to the project.
The University of Sydney received data from Oslo, Vestfold and Vestre Viken in April 2020, and from Bergen in October 2020.
The project group in Australia has merged the data from BreastScreen Norway with screening data from Sweden and Italy. They are currently working on analyzing the data, and aim to publish the first results early 2021.