September 16, 2005

Digital mammography may improve cancer detection

NEW YORK (Reuters Health) - As a screening measure for
breast cancer, digital mammography is more accurate than
conventional mammography at detecting disease in women with
dense breasts, women younger than 50 years of age, and
premenopausal women, new research shows.

Conventional mammography involves the creation of a breast
image directly onto film. With digital mammography, by
contrast, an electronic image is taken and stored in a
computer. The display characteristics of the image can then be
manipulated and the radiologist can use software to help detect
breast abnormalities.

Previous reports have shown that conventional mammography
is limited in its ability to detect cancer in dense breasts,
which are commonly found in younger women, according to the
report released Friday in The New England Journal of Medicine.
Digital mammography was developed to address this and other
limitations of conventional mammography.

Still, despite the apparent advantages for digital
mammography, previous studies have failed to show that it is
more accurate than conventional mammography, lead author Dr.
Etta D. Pisano, from the University of North Carolina in Chapel
Hill, and colleagues note. However, these studies only used one
type of digital detector and did not have enough study
participants to detect small differences in accuracy.

In the Digital Mammographic Imaging Screening Trial
(DMIST), 49,528 women with no signs or symptoms of breast
cancer were screened for the disease with both digital and
conventional mammography. Two radiologists interpreted the

Complete data were available for 86.3 percent of the study
participants. Breast cancer status was determined through
biopsy within 15 months of study entry or with repeat mammogram
at least 15 months after study entry.

The new study compared film mammograms to digital
mammograms from systems made by Fischer Imaging, Fuji Photo
Film Co. Ltd., General Electric Co. and Hologic Inc. All but
the Fuji system are approved by the Food and Drug
Administration and available for use in the United States.

In the overall analysis, digital and film mammography were
similar in their ability to identify breast cancer. As noted,
however, digital mammography was significantly more accurate
than film mammography at detecting cancer in women under 50
years of age, women with dense breasts, and premenopausal

While these findings are encouraging, the adoption of
digital mammography as a routine screening measure will likely
depend on another factor: cost.

"Digital systems currently cost approximately 1.5 to 4
times as much as (conventional) systems," the researchers point
out. "As part of DMIST, we are performing a formal
cost-effectiveness analysis."

SOURCE: The New England Journal of Medicine, September 16,