Clinical Trial on Effectiveness of Breast Cancer Screening Using 3D Mammography

The Breast Health Center in Ottawa, Canada, is the latest site to join the lead-in to the Tomosynthesis Mammographic Imaging Screening Trial (TMIST). This site – which will be part of a larger Canada/US study – will be managed by researchers at The Ottawa Hospital Breast Health Centre and the Ottawa Integrative Cancer Centre (OICC).

The TMIST is the largest multi-center study of its kind to evaluate whether 3D digital tomosynthesis technology used in conjunction with 2D digital mammography, is more effective at early identification of breast cancer, compared to conventional mammography alone. Previous studies have shown that 3D mammography is effective at diagnosing breast cancer before it becomes more advanced, while minimizing the number of false positive results.

If the current trial is able to reproduce these results, 3D mammography could be a more effective and less costly tool for breast cancer screening. The lead-in study will enroll just over 6,000 women across Canada, including approximately 2,000 patients at the Ottawa site alone.

Digital breast tomosynthesis composes a 3D image of the breast tissue by layering multiple images taken using low-dose X-rays. The benefit over traditional 2D mammography is that information in the images compiled using tomosynthesis are not superimposed, reducing the risk of physicians missing hard to see tumors.

“Tomosynthesis is the most advanced and exciting technology for mammography,” said Dr. Jean Seely, Head of Breast Imaging at the Breast Health Centre, associate professor at the University of Ottawa and lead investigator of TMIST Lead-In in Ottawa. “When the full study begins, it will be the largest and most important study to evaluate both 3D and 2D mammography technology together. Outcomes of the study will allow us to decide how we move forward from 2D to 3D screening. Our goal is to improve on ways to detect important cancers as early as possible in order to save lives.”

Screening programs using mammography have been very successful at reducing the mortality rate of breast cancer. Women who underwent screening prior to receiving a breast cancer diagnosis showed a mortality rate of six percent at five years post-diagnosis, while those who were not screened had a 15 percent death rate.

However, like most screening technologies, traditional 2D mammography carries an inherent risk of generating false positive results. This occurrence creates unnecessary stress for patients, with over 90 percent of women recalled for additional testing receiving a benign or normal diagnosis. The hope is that tomosynthesis could improve the accuracy of breast cancer detection, by eliminating most false positives.

“We are pleased to collaborate and help fund this critical trial,” said Dugald Seely, naturopathic doctor, Executive Director of the OICC, and co-investigator of TMIST in Ottawa. “Imaging and mammography are stressful events. The OICC is committed to supporting women so that they receive the best diagnostic technology, limiting unnecessary anxiety and ultimately reducing the burden of disease. The screening program is potentially revolutionary and we hope will be more accurate in correctly finding breast cancers that may not otherwise be diagnosed.”