A new study that enrolled nearly 50,000 women has revealed that digital mammography can detect breast cancer better than conventional film-based mammography in certain groups of women.
Overall, the study showed that conventional film mammography and digital mammography were equally effective. However, digital mammography performed better for the following groups: women under 50, women who are premenopausal and perimenopausal and women with dense breasts. The total of these groups represents at least 50 percent of the general population of women.
Physicians from 33 sites in the U.S. and Canada participated in DMIST (Digital Mammographic Imaging Screening Trial). Investigators at Washington University School of Medicine in St. Louis screened the largest cohort of volunteers in the study, enrolling more than 3,300 patients at the Joanne Knight Breast Health Center, which is affiliated with Barnes-Jewish Hospital and the Siteman Cancer Center.
Scientists announced the results of DMIST today at the fall meeting of American College of Radiology Imaging Network (ACRIN). It is simultaneously being published online by The New England Journal of Medicine. The National Cancer Institute funded the DMIST trial.
"From the patient''s perspective, the digital mammogram experience is the same as a conventional mammogram," says Dione Farria, MD, assistant professor of radiology at Mallinckrodt Institute of Radiology and principal investigator for the DMIST study site at Washington University Medical Center. Both technologies require X-rays and breast compression to obtain an image.
"Unlike conventional film mammography, though, digital mammography stores a digital image of the breast in a computer," Farria says. "This allows radiologists to use computer software to manipulate the images in order to optimize their ability to evaluate the breast tissue."
Farria notes that the DMIST results do not mean that women who have had conventional mammograms need to go back to their doctors immediately and request a digital mammogram."Since only eight percent of mammography units in the United States are digital units, it will not be possible for all women to receive digital mammograms in the near future," she says. "Furthermore, the study showed that digital mammograms did not offer an advantage to all women."
Researchers emphasize that it is important for women to continue having routine screening mammograms, because it has been scientifically proven that conventional mammography saves lives by detecting breast cancers earlier.
"Whether a facility has digital or conventional film mammography is only one factor to consider when choosing a mammography facility," Farria says. "The expertise of the radiologists who read the mammograms and the skill of the technologists are probably equally -- if not more -- important. While it is highly likely that we are going to see a transition from film to digital mammography, several factors will influence the speed of this change. "
Cost is a potential limiting factor in expanding the use of digital mammography. While a traditional mammography unit typically costs about $75,000-100,000, digital units with the required computer workstation may costs 3- 5 times more.
Since digital mammography is significantly more expensive than conventional mammography, DMIST investigators plan to conduct an analysis of the new technology in the context of its cost-effectiveness. Researchers are also concerned about the ability of small mammography facilities to raise the capital necessary to convert to digital technology.
In women, breast cancer is the most common malignancy and the second leading cause of cancer death. Last year, there were more than 215,000 new cases of invasive breast cancer and over 40,000 breast cancer-related deaths in the United States. In the state of Missouri in 2004, the American Cancer Society estimates that 4,680 women were diagnosed with breast cancer and 870 women died from breast cancer.
Women wishing to obtain more information about the results of the DMIST study may contact the Siteman Cancer Center at (314) 747-7222 or 1-800-600-3606.
###
Pisano ED, et. al., for the Digital Mammographic Imaging Screening Trial Investigators Group. Diagnostic performance of digital versus film mammography for breast-cancer screening. The New England Journal of Medicine, online publication.
Funding from the National Cancer Institute supported this research.
Washington University School of Medicine''s full-time and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children''s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked third in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children''s hospitals, the School of Medicine is linked to BJC HealthCare.