Digital mammograms better for some women

BY Mike Grippi

September 16 2005 11:00 PM ET

Newer mammograms
that allow doctors to use digital imaging to help spot
cancer are better than standard X-rays for young women and
those with dense breasts but not for most
postmenopausal women, a landmark study concludes.

Doctors say women
who aren’t in one of the groups that benefited can
skip the extra cost of the newer digital tests and
have a standard mammogram. However, they expect
digital tests to become more common because of their
many advantages, including that they can be stored on a
computer and sent electronically whenever a woman
moves or a new doctor needs to see them.

“Everything is going filmless. If there’s no
disadvantage to digital mammography, I would presume
over time it will replace film screening,” said
Kathy Brandt, chief of breast imaging at the Mayo Clinic in
Rochester, Minn., who had no role in the study.

The study, funded
by the National Cancer Institute, involved 42,760 women
in the United States and Canada and was done by the American
College of Radiology Imaging Network. Results were to
be reported Friday at a medical meeting. They also
were released online by the New England Journal of
Medicine
and will appear in its October 27
edition.

Mammograms cut
the risk of breast cancer deaths by up to 35% among
women 50 and older but only by 15% to 20% among younger
women, who tend to have dense breasts that standard
film X-rays have trouble penetrating.

Digital
mammograms produce images on a computer screen, where they
can be enhanced or magnified to reveal lurking signs
of cancer. Doctors have hoped that this would improve
mammography’s usefulness for younger women.

The study aimed
to learn whether they are more accurate; that is, whether
they correctly detected cancer and didn’t give too
many “false alarms.”

Each participant
received both types of mammograms. Results were reviewed
independently by two radiologists, and biopsies settled
whether suspicious findings were cancer. Follow-up
exams were done a year later to see how many cancers
had been missed the first time around. A total of 335
breast cancers were found; both types of mammograms missed
about 30% of them. Digital mammograms proved 15% more
accurate than standard film X-rays among women under
50, in whom breast cancer is relatively uncommon.
Among women with dense breasts and those not yet in
menopause, digital mammograms were 11% and 15% better,
respectively.

For all other
women, “film is just as good,” said Etta
Pisano, a radiologist at the University of North
Carolina at Chapel Hill who led the study. She said
the results should help prioritize who gets the more
expensive tests: “We don’t have enough digital
mammography for everyone to get it, and some women
won’t benefit from it anyway.”

The first digital
machines came on the U.S. market in 2001, but they
account for only 8% of mammography equipment today, largely
because of cost. Medicare pays an average of $85.65
for a standard film mammogram and $135.29 for a
digital one.

Robert Smith,
director of screening at the American Cancer Society, said
no woman should delay getting a mammogram if a digital one
is not available. The society recommends that annual
mammograms start at age 40; the federal government
advises them every one to two years for women in their
40s and then annually starting at age 50.

As for the study
results, “we’d always like a newer technology
to do better in every way,” but improving
mammograms for certain groups of women is still a
gain, he said.

In the study,
about two thirds of women either had dense breasts, were
under 50, or had not reached menopause. That led Daniel
Sullivan, who heads cancer imaging at the National
Cancer Institute, to conclude, “It may not be
completely representative of the general population”
because most mammograms are done on women over 50 who
have fatty breasts.

The study was the
largest ever done to compare mammography techniques.
Earlier studies have found digital mammograms to be
comparable in accuracy to film for women in general.
(AP)

Tags: Health

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