MRI
Helps Find Breast Cancer In High-Risk Women
More Evidence
Points To MRI Usefulness
For a small group
of women with a genetic or family history for breast cancer,
regular magnetic resonance imaging (MRI) breast screening may
be the best way to spot tumors early, according to a report
in the New England Journal of Medicine.
While mammography
is mostly effective in spotting tumors, a small percentage of
women - such as those carrying the BRCA1 or BRCA2 breast cancer
genes - may need screening technologies with even greater powers
of detection.
Magnetic resonance
imaging (MRI) is a diagnostic procedure that uses a combination
of a large magnet, radiofrequencies, and a computer to produce
detailed images of organs and structures within the body.
Breast cancer remains
the second leading cause of cancer death among US women.
The American Cancer Society estimates that
215,990 new cases of invasive breast cancer will be diagosed
in the US in 2004.
For women at high
risk for breast cancer, "In their lifetime, 50 to 85 percent
of these women will develop breast cancer," explains Dr. Laura
Liberman, a radiologist at the Breast Imaging Section at
Memorial Sloan-Kettering Cancer Center in New York City.
MRI Spots
Cancer More Often
In the new study,
breast MRIs conducted annually were nearly 80 percent effective
in picking up invasive cancers in high-risk women, compared
to the 33 percent effectiveness rating of annual mammograms,
researchers report.
However, experts agree
that MRI's high rate of false positive results - findings that
could be malignant tumors, but turn out to be benign - make
the technology much less desirable for women at normal breast
cancer risk.
While regular MRI
breast scans may be of benefit to women at high risk, "women
at normal risk should not be encouraged to undergo regular MRI
screening," said study author Dr. Jan G. M. Klijn, a medical
oncologist at the Netherlands' Rotterdam Family Cancer Clinic.
Dr. Liberman, who
wrote an editorial accompanying the Dutch study, said that for
these women, an annual mammogram is not enough. "So, people
are now studying supplementary techniques, such as MRI," she
says.
In their study, Dr.
Klijn's team selected 1,909 adult women who were either carriers
of the BRCA1 or BRCA2 genes, or who had a strong family history
of breast cancer - defined as close relatives diagnosed with
breast tumors before age 30.
All of the women received
clinical breast exams every six months, plus mammography and
MRI screening annually, over the course of three years.
Fifty-two breast cancers
were detected among the group during the study period, the researchers
report.
In terms of early
detection, MRI far outperformed mammography or clinical breast
exams. MRI was also much better at detecting very small tumors
(10 millimeters or less in diameter) at a very early stage.
Based on the findings,
Dr. Klijn says, "Our recommendations are to use MRI as a screening
method in specialized facilities, for women with a BRCA
[1 or 2]mutation or a really high risk of breast cancer."
Save MRI
for High-Risk Women
Both Drs. Klijn and
Liberman are careful to not extend this recommendation to women
at average risk, however.
Dr. Liberman explains
that, besides the scarcity and high cost of MRI, the technology's
strength - its ability to spot very tiny abnormalities in tissue
- is also a weakness.
"This is a very sensitive
test," she says. "If there's a cancer hiding in the breast,
it's likely to show up. But as a tool it's also not very specific,
meaning that a lot of normal stuff will light up, too."
That may be acceptable
for the anywhere from 1 percent to 10 percent of women at very
high risk for breast cancer, she says. For these women, "If
you have a positive result, the likelihood that it's [a tumor]
is so much higher" that it may be worth going to the next step,
which is biopsy, Dr. Liberman explains.
On the other hand,
MRI's high false-positive rate "would simply cause a lot of
anxiety and then lead to a lot of unnecessary, benign biopsies
if we started to apply it as a screening test in the general
population," she says. "There's just no evidence that it's a
helpful screening test in women at normal risk."
Always consult your
physician for more information. |
September 2004
MRI
Helps Find Breast Cancer In High-Risk Women
MRI
Spots Cancer More Often
Save
MRI for High-Risk Women
What
Is Magnetic Resonance Imaging (MRI)?
Online
Resources
What
Is Magnetic Resonance Imaging (MRI)?
Magnetic resonance
imaging (MRI) is a diagnostic procedure that uses a combination
of a large magnet, radiofrequencies, and a computer to produce
detailed images of organs and structures within the body.
The MRI machine is
a large, cylindrical (tube-shaped) machine that creates a strong
magnetic field around the patient.
The magnetic field,
along with a radiofrequency, alters the hydrogen atoms' natural
alignment in the body.
Computers are then
used to form a two-dimensional (2D) image of a body structure
or organ based on the activity of the hydrogen atoms.
Cross-sectional views
can be obtained to reveal further details. MRI does not use
radiation, as do x-rays or computed tomography (CT scans).
A magnetic field is
created and pulses of radio waves are sent from a scanner. The
radio waves knock the nuclei of the atoms in your body out of
their normal position.
As the nuclei realign
back into proper position, they send out radio signals. These
signals are received by a computer that analyzes and converts
them into an image of the part of the body being examined.
This image appears
on a viewing monitor. Some MRI machines look like narrow tunnels,
while others are more open.
MRI may be used instead
of computed tomography (CT) in situations where organs or soft
tissue are being studied, because with MRI scanning bones do
not obscure the images of organs and soft tissues, as does CT
scanning.
Always consult your
physician for more information.
Online Resources
(Our Organization
is not responsible for the content of Internet sites.)
American
Cancer Society
American
Society for Clinical Oncology
Centers
for Disease Control and Prevention (CDC)
National
Cancer Institute
National
Institutes of Health (NIH)
National
Women's Health Information Center
Susan
G. Komen Breast Cancer Foundation |
