Cancer Research Women's health

Behind the research: 2D or 3D mammography for breast cancer screening?

digital mammogram

When new technology is invented, it’s often instantly thought to be “better” at everything.

But when it comes to breast cancer screening, is 3D mammography actually better than traditional 2D mammography at spotting cancers that are aggressive?

That’s what Dr. Martin Yaffe, a senior scientist at Sunnybrook and co-lead on the TMIST trial, is hoping to find out. That, and more.

The randomized trial, which is open now at Sunnybrook and Ottawa Hospital as well as in hospitals across the US, will compare the two types of digital mammography to help researchers learn how to most effectively screen women for breast cancer and help women in the future make informed decisions about screening tests.

3D mammography (called tomosynthesis) is currently used as a diagnostics tool if a woman has a suspicious mass. But, in Canada, it isn’t currently used in breast screening programs because its value for screening has not yet been fully tested.

Since 2014, Dr. Yaffe and his team at Sunnybrook have been conducting a lead-in study to TMIST with over 3,000 women at four sites in Canada.

The TMIST trial (coordinated in Canada by the Canadian Cancer Trials Group and available at more screening locations across the nation over the next few months) is now enrolling 165,000 healthy women ages 45 to 74 who are already planning to get routine mammograms. They will be randomized to receive 2D or 3D mammograms for 5 years.

Dr. Yaffe says the study will answer questions like:

  • Does the 3D technology actually reduce false alarms from screening?
  • Can it find more cancers?
  • Does the 3D technology reduce a woman’s chance of getting advanced and aggressive cancer compared with 2D technology?

Clinical trials like this are important, Dr. Yaffe says, because they can help researchers, clinicians and ultimately patients make better-informed decisions about screening.

“We know breast cancer screening is important,” he says. “How best can we screen in order to catch aggressive cancers so that we can treat them early?”


More Resources:

Learn more about the lead-in study, which was led by Sunnybrook

Canadian Cancer Trials Group

ECOG-ACRIN Cancer Research Group

About the author


Alexis Dobranowski

Alexis Dobranowski is a Communications Advisor at Sunnybrook.