BETHESDA, Maryland—The first large, multicenter study to compare digital vs standard film mammography has begun enrolling patients. The Digital Mammographic Imaging Screening Trial (DMIST) will study 49,500 women at 18 centers in the United States and one center in Canada.
"We want to make sure digital mammography is at least as good as standard mammography at finding early breast cancer," said principal investigator Etta D. Pisano, MD, professor of radiology, University of North Carolina, Chapel Hill. "We expect there will be an advantage, but none of the early studies has shown a real benefit of digital over film."
The American College of Radiology Imaging Network, a National Cancer Institute-supported clinical trials group, will conduct the $26.3 million study. Women will be enrolled at the time of their regular screening mammogram. Researchers expect to complete patient accrual in 18 months, and participants will be followed for at least 1 year.
Each woman will receive a two-view digital mammogram and a two-view film mammogram of each breast. Each of the two screenings will be interpreted independently, and patients will undergo workups based on abnormal findings from either exam. One year later, researchers will repeat the screenings using the same protocol.
"Truth regarding breast cancer status for all patients will be determined either through the results of breast biopsy, if that occurs, or as a result of 1 year of follow-up without clinical evidence of disease," NCI said. "All pathologic specimens will be reread by an expert breast pathologist."
The radiation dose will be the same for both digital and standard mammograms in the study. "We can certainly get the same information out of a digital mammogram at a lower dose than film, but we might be able to get more information at a higher dose," Dr. Pisano said.
In addition to the primary endpoint of efficacy, researchers will seek to determine the effect of breast density on the diagnostic accuracy of digital mammography. Other secondary objectives of DMIST include:
- Determining the effects of patient characteristics (such as age, lesion type, pathologic diagnosis, hormonal status, and family history) on the diagnostic accuracy of digital mammography.
- Assessing the effect of the reduced false-positive tests that are expected with digital mammography on participants’ health-related quality of life and personal anxiety.
- Comparing the diagnostic accuracy of soft copy vs printed film display for digital mammography.
- Comparing the image quality and breast radiation dose in digital vs screen-film mammography.
- Determining the temporal variations in image quality, breast radiation dose, and other quality-control parameters in the participating study centers.
