Geller and Colleagues’ Study Examines Accuracy of Digital Compared to Film Mammography
- By Jennifer Nachbur
Over the past few years, newer digital mammography has been replacing older film mammography, but researchers wondered, is the newer technology better at detecting cancer? A new study reported October 18, 2011 in the Annals of Internal Medicine and coauthored by Berta Geller, Ed.D., professor of family medicine at the University of Vermont College of Medicine, is the first to assess the accuracy of digital compared to film mammography in U.S. community practice.
Geller is principal investigator of the Vermont Breast Cancer Surveillance System, which is part of the National Cancer Institute’s Breast Cancer Surveillance Consortium (BCSC) – an NCI-funded collaborative network of seven mammography registries with linkages to tumor and/or pathology registries. For this study, she and colleagues examined data that were pooled from four mammography registries – including Vermont’s – that participate in the BCSC and collect data from at least one facility that performs digital mammography.
The team examined bilateral digital and and filmscreen mammography examinations performed between January 1, 2000 and December 31, 2006 among women aged 40 to 79 years who did not have a history of breast cancer or breast implants. A total of 869,286 screening mammography examinations (231,034 digital and 638,252 film-screen) were performed among the 329,260 women aged 40 to 79 years. The authors note that breast cancer was diagnosed in 4,046 women (1,054 digital and 2,992 film-screen examinations), primarily at nonacademic facilities (83 percent).
The researchers found that both types of mammograms – digital and film – performed similarly for women age 50 to 79 for detecting cancer. But for women in their 40s who have not gone through menopause and who have dense breasts, digital mammography may be better than film mammography at detecting cancer. However, the researchers found that in women age 40 to 49, the risk of false positives was somewhat higher with digital than with film mammography.
The NCI funded this study. The collection of cancer data was also supported in part by several state public health departments and cancer registries throughout the United States.
About Digital Mammography (Source: National Cancer Institute)
Digital and conventional mammography both use x-rays to produce an image of the breast; however, in conventional mammography, the image is stored directly on film, whereas in digital mammography, an electronic image of the breast is stored as a computer file. This digital information can be enhanced, magnified, or manipulated for further evaluation more easily than information stored on film. The FDA approved the use of digital mammography in January 2000. In September 2005, preliminary results from a large clinical trial that compared digital mammography with film mammography were published. These results showed no difference between digital and film mammograms in detecting breast cancer in the general population of women in the trial. However, the researchers concluded that digital mammography may be more accurate than conventional film mammography in women with dense breasts who are premenopausal or perimenopausal (i.e., women who had their last menstrual period within 12 months of their mammograms) or who are younger than age 50. Whether this improved accuracy will translate into a reduced risk of breast cancer death is not yet known. Digital mammography can be done only in facilities that are certified to practice conventional mammography and have received FDA approval to offer digital mammography. The procedure for having a mammogram with a digital system is the same as with conventional mammography.
(This article was adapted from a news release produced by Rebecca Hughes, senior media consultant at the Group Health Research Institute.)