Australian Trial Supports Efficacy of 3D Mammography for Breast Cancer Assessment
The first Australian clinical trial of 3D breast imaging technology - or tomosynthesis - in the assessment of breast cancer has produced highly promising results.
The trial, undertaken over a 14-month period from January 2013 at BreastScreen Victoria’s Maroondah service in outer eastern Melbourne, involved 560 women. All the women had been recalled for further tests after routine screening mammograms using conventional 2D x-rays had detected breast abnormalities.
The trial did not explore the use of tomosynthesis for the initial mammograms undertaken as part of general population screening for breast cancer amongst women attending BreastScreen.
The findings were unveiled today by the trial’s Principal Investigator, Dr Darren Lockie, the Designated Radiologist of Maroondah BreastScreen, at the annual conference of BreastScreen Australia in Melbourne.
The trial found:
- Tomosynthesis provides a more detailed, 3D image of the breast, reducing the risk of missing cancers
- Tomosynthesis could reduce the need for further assessment tests - biopsies by 27% and ultrasound by 11%
- Four in five participants (81%) found the assessment experience, including the compression, with tomosynthesis much better, better or the same as for their 2D screening mammogram
- Four new cancers not detected in the original screening mammograms were identified
- Used in place of regular 2D mammograms, the radiation dose is comparable, and often less than existing X-ray practice and within the guidelines.
Digital breast tomosynthesis (DBT) uses a specifically designed digital mammography unit to produce 3D images. A number of low dose conventional x-rays of the compressed breast are taken from different angles and then reconstructed into a 3D volume of thin “slices” through the breast using mathematical algorithms.
Dr Lockie said: “In the assessment of women from screening programs identified as needing further investigations it’s unequivocal that tomosynthesis absolutely has a role. There’s growing evidence now that it’s a valuable test.”
I see this as a technology that has clear benefits for our clients and has clear benefits for clinicians, as it increases diagnostic confidence.
“The flow-on effects are that it has benefits for the health system because there would be cost savings as you may need fewer tests to come to a definitive outcome.”
While the trial involved a combination of 2D and 3D x-rays that increased the radiation dose for participating women, a new technique developed since the trial and involving 3D scans plus computer-generated 2D images (from the 3D information) would overcome this concern moving forward, Dr Lockie said.
“There would be a small increase in radiation dose but a 30-40% increase in the cancer detection rate using a combination of tomosynthesis and computer-generated images,” he said.
BreastScreen Victoria CEO Vicki Pridmore said: “The results of the Maroondah trial look very promising for the future use of tomosynthesis in the post-screening assessment of breast cancers.”
“However, until we see it trialled in a broader clinical screening setting and as a replacement for 2D mammography, we will not have a clear picture of the benefits and costs of using tomosynthesis for population screening generally in the BreastScreen Australia service.”
“It is also an expensive technology so we would need to be sure we were making a sound investment that delivers significant and long-term benefits before rolling it out across Victoria or nationally,” Ms Pridmore said.
Any decision to endorse the use of tomosynthesis in BreastScreen assessment services will be taken nationally by BreastScreen Australia, on the advice of the Federal Government’s Standing Committee on Screening. Rollout will then be subject to the timelines and funding capacities of individual states and territories.