A trial comparing standard mammograms with a new type of digital mammogram to screen for breast cancer (TOMMY Trial)

Cancer type:

Breast cancer





Breast screening is recognised to be the best way to find early stage breast cancer, and to reduce the number of deaths from this disease. Doctors use breast X-rays (mammograms) to screen for breast cancer. Current mammograms give 2D pictures of the breast.

But sometimes, it is possible that breast changes may be missed on these mammograms because they are hidden by overlapping normal breast tissue. And, in other cases, healthy tissue that overlaps may look like changes that are a cause for concern. This means women have to come back for further checks, causing unnecessary anxiety.

This trial looked at a method called digital breast tomosynthesis (DBT), which uses digital X-rays and a computer to put together 3D pictures of the breast. We know from early research that tomosynthesis reduces the problem of overlapping tissues. This helps the doctor to see the structures of the breast more clearly. The aim of this trial was to compare the accuracy of tomosynthesis and standard mammograms when diagnosing breast changes found during screening.

Summary of results

The trial team found that using 2D mammograms and digital breast tomosynthesis (DBT) together found slightly more breast cancers and could also help reduce the number of times women are called back for more tests.

The trial compared

  • A 2D mammogram
  • A 2D mammogram and digital breast tomosynthesis (DBT)
  • Synthetic 2D mammogram and DBT

A synthetic 2D mammogram is when the 2D images of the breast are created from DBT. The researchers looked at this as they thought it would reduce the amount of radiation women are exposed to in comparison to having both a standard mammogram and DBT.

The researchers looked at which test or combination of tests was most accurate in finding breast cancer.

Images were collected and looked at in one of 6 local centres.  2 people called film readers or image readers looked at the mammogram and DBT and checked for any signs of cancer. The film readers were either radiologists Open a glossary item, radiographers Open a glossary item or specialist breast cancer doctors.

The images were then sent to the trials office who sent them out to 3 separate places to be reviewed again. The researchers made sure that different readers looked at the images every time.

In total 8869 people took part in the trial. Some people had to be excluded and in the end the researchers looked at images from

  •  6021 women aged between 43 and 73 who had been recalled for more tests after routine breast screening
  • 1040 women aged between 40 and 49 who have a family history of breast cancer and have annual breast screening

After looking at the results of images the researchers concluded that combined 2D and DBT imaging was slightly better at finding breast cancer than 2D alone. They found this in all age groups and breast density. The term ‘breast density’ describes how breasts look on a mammogram.

They stated that as the Breast Screening Programme is due to be extended to include younger women this could be an advantage as younger women often have denser breast tissue.

The researchers also think that using 2D and DBT imaging could reduce the amount of women who are recalled for further tests and so lessen the amount of anxiety and stress linked to this.

The trial team have suggested further areas of research including

  • Looking at how cost effective it would be to introduce DBT into the Breast Screening Programme
  • The use of DBT in younger women
  • The use of synthetic 2D mammograms

We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Professor Fiona Gilbert

Supported by

Experimental Cancer Medicine Centre (ECMC)
NIHR Health Technology Assessment (HTA) programme
National Institute for Health Research Cancer Research Network (NCRN)
University of Cambridge

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Deborah wanted to help other breast cancer patients in the future

A picture of Deborah

“Deborah agreed to take part in a trial as she was keen to help other cancer patients in the future. "If taking part in a trial means others might be helped then I’m very happy with that."

Last reviewed:

Rate this page:

No votes yet
Thank you!
We've recently made some changes to the site, tell us what you think