Two major studies addressing breast cancer detection were
published recently. One attempted to quantify the widely
acknowledged role of screening mammography in the reduction of
breast cancer mortality; the other addressed the issue of the
relative efficacies of digital and analog mammography for breast
The Cancer Intervention and Surveillance Modeling Network
(CISNET) Collaborators used 7 independent statistical models of
breast cancer incidence and mortality to assess the relative and
absolute contributions of screening mammography and adjuvant
treatment in the nearly 25% decline in breast cancer mortality seen
in the United States since 1975.
The various models showed that screening mammography was
responsible for 28% to 65% of the reduction, with a mean reduction
of 46% between the models. Adjuvant treatment was credited with the
remainder of the decrease.
The DMIST study
For clinicians, however, the current question is which
mammography technology-digital or analog-is going to help them find
the most cancers as early as possible. The Digital Mammographic
Imaging Screening Trial (DMIST) was designed to compare the
sensitivity of digital mammography with that of film-based
mammography for breast cancer detection.
This large-scale 2-year study, conducted by the American College
of Radiology Imaging Network, included more than 42,000 women in
the final data analysis. Initially, more than 49,500 asymptomatic
women who presented for screening mammography at 33 sites in the
United States and Canada underwent both film-based and digital
mammography, in random order, on 1 of 5 first-generation digital
mammography systems: The SenoScan from Fischer Medical (Denver,
CO); the Computed Radiography System for Mammography from FUJIFILM
Medical Systems USA (Stamford, CT); the Seongraphe 2000D from GE
Medical Systems (Waukesha, WI); and the Digital Mammography System
and the Selenia Full-Field Digital Mammography System from Hologic,
Inc. (Bedford, MA).
All mammograms were interpreted independently by 2
radiologists-one read the film and the other read the digital
image-using a 7-point malignancy scale and the BIRADS
classification. Biopsies or aspirations of suspicious lesions were
performed if either of the radiologists recommended the procedure.
A participant was classified as positive for breast cancer if
cancer was pathologically verified within 455 days of the initial
Data were compared for all participants and across a variety of
subgroups, including age (younger or older than 50 years), breast
density (heterogeneously dense, extremely dense, or less dense),
menopausal status (pre-, peri-, or postmenopausal), race (white,
black, or other), and lifetime risk of breast cancer (>25% or
<25%), as determined by the Gail model.
A total of 335 breast cancers were diagnosed during this study.
The authors reported finding no significant difference in the
overall accuracy of the 2 methods, nor did they find any
significant difference in accuracy between film and analog
mammography in relation to race, the patient's breast cancer risk,
or the brand of system used. The authors concluded that "the
overall diagnostic accuracy of digital and film mammography . . .
is similar, but digital mammography is more accurate in women under
the age of 50 years, women with radiographically dense breasts, and
premenopausal or perimenopausal women." They also reported that
cancers detected with digital mammography that were missed on film
included many invasive and high-grade in situ cases.
The importance of DMIST
"I think what makes this study important is the fact that the
results demonstrated that there is technology out there that can
actually improve the diagnostic accuracy of mammography for women
in particular subgroups," said Andy Vandergrift, National Program
Director for Women's Health Care Imaging at FUJIFILM. "The
subgroups that were mentioned actually represent a majority of the
screening population: 65% of the 49,000+ women who participated in
DMIST fell into at least one of those categories. Since it was such
a large study, I think that we can at least draw the conclusion
that the majority of the women in the screening group would benefit
from digital mammography."
John Pavlidis, President and Chief Executive Officer of R2
Technology, Inc. (Sunnyvale, CA) agreed. "It is the most
significant study of its kind," he said. "It is very comprehensive
and has very credible methodology. It's the only study of this
scale that really compares film-based and digital mammography. It's
been long and eagerly awaited and its publication is a major
milestone. It shows how a forward step in technology can help
radiologists have greater accuracy in evaluating mammograms."
Georgia Hitzke, Vice President of Clinical Development at
Hologic was most impressed with the findings in women with dense
breasts. "Patients with dense breasts are at the highest risk for
breast cancer and we've always tried to optimize technology for
these women," she said. "I think there is a fallacy about
postmenopausal women-that older women don't have dense breasts.
DMIST showed that 40% of them do have dense breasts. So there is a
large population-it's not just the younger people that we have to
make sure we can diagnose; it is all ages."
The continuing role of analog mammography
This does not, however, mean that there is no longer a role for
analog mammography. From a practical standpoint, there are
relatively few digital mammography systems currently installed in
the United States. "In terms of the installed base for digital
systems, I understand that it is approximately 8%, but the growth
rate for digital has been quite high," explained Pavlidis. "It is
reportedly 35% to 40% per year. Our sense is that this will further
accelerate the adoption of digital mammography."
Furthermore, the study found that, in some instances, analog
mammography showed some lesions that digital missed. "DMIST said
that digital was better in dense breasts, but film-screen was equal
or maybe just a little bit better in fatty breasts," said Hitzke.
"We want to be sure that people still get film-screen mammography
on a good system. It doesn't make a difference which manufacturer
it is, but it is important that it is a good system for dense
breasts or any type of breast, because it will pick up
microcalcifications and other lesions. This study just shows that
digital can sometimes pick up different types of things or maybe
pick them up a little bit earlier in certain populations."
"It should be stressed that film-screen mammography is still
very good and it's the best screening tool we have today to
diagnosis breast cancer," agreed Vandergrift. "I think it still is
the gold standard; however, as new technologies, such as digital
mammography, are introduced, they are typically compared with the
standard. What we see here is that the new technology actually
offers advantages, and that is how change comes about."
"I think the study definitely says that there will be an ongoing
role for film-based mammography," added Pavlidis. "The benefits
seen with digital were evident in a subset of the population. That,
by no means, implies that there is no benefit for analog
mammography. Interestingly enough, it is also important to note
that the improvement in detection with digital over analog in the
study is similar or even smaller than the improvement in detection
by adding computer-aided detection (CAD) to either digital or
Use of CAD in mammography
"CAD was not part of the study," continued Pavlidis, "But CAD is
a proven technology that increases cancer detection rates, and CAD
works for both analog and digital mammography. Published rates
range from a 7.4% to 19.5% increase in cancer detection. We have
seen a very high adoption rate of CAD in association with either
analog or digital mammography sales. We believe that the DMIST
study will further accelerate the adoption rate for digital
"The interesting thing about this study is that a lot of the
technology used is already old technology," added Hitzke.
"Currently available digital technology is actually better. A lot
of us thought the 2 types of systems might be equal, so I was
pleasantly surprised by the results. Given the technology we have
today, I think that digital will be even that much better than
"The study shows that we are moving in the right direction with
digital," concluded Hitzke. "Full-field digital mammography is
good, and the most important thing on these systems is image
quality and the best detection. To me, getting the best technology
is a cause worth fighting for. I am happy that something great came
out of this study."