Effectivness of tomosynthesis in breast cancer screening

An international study that will investigate whether tomosynthesis is a better screening technique for breast cancer than standard digital mammography.

Published 18 December 2019


There is accumulating evidence that digital breast tomosynthesis (DBT) increases the detection rate and reduces the recall rate in population-based screening for breast cancer compared to standard digital mammography (DM).

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 wants 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.


BreastScreen Norway will participate by providing screening information stored at the Cancer Registry of Norway, in accordance with the Cancer Registry Regulations (kreftregisterforskriften).

The Cancer Registry of Norway will initially contribute with data from about 100,000 women aged 50-69 who were screened through BreastScreen Norway in Oslo, Vestfold and Vestre Viken in 2014 and 2015 through the OVVV-study. The Cancer Registry of Norway will only send data from women who have consented to their personal data related to negative screening results being permanently stored at the Registry.

Later, the Cancer Registry of Norway will also contribute with data from about 40,000 women aged 50-60 who were screened through BreastScreen Norway in Bergen between 2016 and 2019, and who consented to participate in the To-Be study.

The project team will not contact women whose data will be used in 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 getting necessary approvals in Australia.

The Cancer Registry of Norway is a project collaborator and is responsible for getting 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 getting necessary ethical approvals and delivering data from studies performed in their countries to the project.