Mammography Still the 'Gold Standard' for Breast Cancer
Is Mammography still the best?
"Many consider [digital mammography] to be a major
technical advance over traditional mammography, but studies to date have not
demonstrated a meaningful improvement in screening accuracy," the report
says. The FDA approved one digital mammography device last year.
Panel member Janet Baum, MD, associate professor of radiology
at Harvard Medical School, says the jury's still out on digital
"It may be better information to some patients [with dense
breasts]," Baum tells WebMD.
There also are other alternatives that may prove effective as
screening tools, such as high-frequency ultrasound waves that bounce off the
tissue and can then be assembled into a map. A new 3-D ultrasound displays
tissue in depth, not just a single slice.
Magnetic Resonance Imaging, or MRI, has been used to look
inside the body with great accuracy since the mid-80s. Now it might be used to
seek out breast tumors that require minimal surgery. Still, this approach may
not be as effective in separating out nonmalignant vs. malignant tumors.
For decades, researchers have thought it would be possible to
illuminate cancers by shining a light source against the breast and looking at
the differences in wave transmission through the tissue. The latest effort
involves using techniques that can measure the chemical and molecular
components of the breast.
Another option, this one being developed at Harvard, is a
handheld scanner that contains pressure scanners that can be moved gently
across the breast. The image is generated in as little as 20 seconds without
painful compression of the tissue.
To expedite the development of new breast cancer screening
approaches, the panel suggests more studies in a variety of areas, with funding
coming from several sources. The report also urges Congress to create greater
access to mammography through the CDC's screening program. State legislatures
also could pick up some of the tab for more poor women through the Medicaid
program, the IOM says.
"We're urging that funding be raised to enable them to
reach at least 70% of women who don't have access because they have no method
of paying," Lashof tells WebMD.
In addition, the IOM wants to see the development of cancer
specimen or tumor banks that can help identify genetic changes or biomarkers in
breast malignancies at all stages of development. That could lead to a blood
test that might eliminate the need for mammography.
The NCI's Kramer says that it's hard to know when to launch a
large clinical trial, particularly since new technologies are always being
developed. Whatever the machine, he argues that longer survival is the crucial
measure of any screen. "Often the tests are embraced before their medical
benefits and harms have been tested," he says.
The panel didn't look at the question of when to begin
screening. The federal government currently recommends that women have the
procedure every one to two years starting in their 40s. The panel did say,
though, that there should be further studies to define more accurately the
risks and benefits of mammograms for women over age 70.