Use of breast MRIs has
nearly tripled in recent years, but the women who could benefit the most are
not always getting the expensive imaging test, a new study suggests.
The research points ups an
important message, said Dr Shelley Hwang, chief of breast surgery at Duke
University Medical Centre in Durham, North Carolina. "More screening is not
necessarily better. Smarter screening is better," said Hwang, author of a
commentary accompanying the study. Both were published online in the journal JAMA
The study found many more
women at high lifetime risk of developing breast cancer – a group advised to
consider MRI – are getting the test than in years past. Those numbers rose
from 9% in 2005 to 29% in 2009.
These results "suggest
that breast MRI is being used better," said lead researcher Karen Wernli,
an assistant investigator at the Group Health Research Institute in Seattle.
However, in a separate but
related study reported in the same issue, Harvard Medical School researchers
found that breast MRIs between 2000 and 2011 jumped 20-fold, then declined and
stabilised by 2011. But fewer than half of women with documented genetic mutations
that raise the risk of breast cancer got the highly sensitive tests, they
Under guidelines on use of
breast MRI, the American Cancer Society and the National Comprehensive Cancer
Network advise considering MRI if a woman's lifetime risk of breast cancer is
greater than 20%. In the general population, a woman's lifetime risk is about
Women considered high risk
are those known to have the genetic mutations BRCA1 and BRCA2, those who had
chest radiation during childhood, or those with a first-degree relative known
to have the BRCA1 or BRCA2 mutation, Wernli said.
For high-risk women, annual
MRIs and mammograms are recommended.
More expensive than mammogram
MRI uses a strong magnetic
field and radio waves, not X-rays, to produce a detailed image. A scan takes
about an hour. The patient lies inside a narrow tube, face down on a platform
with openings so the breasts aren't compressed. Sometimes a contrast material
is injected by IV to show tissue details.
The scan is more expensive
than a mammogram. For instance, Medicare and Medicaid reimburse $880 to about
$1 600 for MRIs of both breasts, and $300 for a digital mammogram. Fees for
women not on Medicare range greatly.
Although MRIs are more
sensitive in finding cancers than mammograms, false positive results are also
more likely, according to research. And that can lead to unnecessary testing,
anxiety and biopsies.
Wernli said she and her
colleagues "wanted to see why women were getting MRIs and how these
patterns changed over time." This is important to ensure that health care
funds are used wisely, they said.
Her team looked at data
from five national breast cancer registries from 2005 to 2011. They found the
overall rate of breast MRIs nearly tripled, from about four exams for every 1000
women to almost 12, during that period. Most commonly, MRI was used to diagnose
or screen for breast cancer.
In the other study, the
Harvard researchers evaluated more than 10 000 women, aged 20 and older, who
had at least one breast MRI. They found breast MRIs increased dramatically from
2000 to 2009, before stabilising. Most of the tests were done for screening or
When they looked at a
subset of the women who received MRIs, only 21% met the cancer society
To learn more about breast
MRI, visit American Cancer Society.