MRI Detects Early Breast Cancer Cells
Study Shows MRI Screening Has High Detection Rate of Precancerous Cells
Aug. 9, 2007 -- MRI screening has been considered less sensitive than
mammography for detecting precancerous cells in the breast which are confined
to the milk ducts, but a new study suggests the opposite is true.
Breast MRI detected 92% of surgically confirmed cases of ductal carcinoma in
situ (DCIS) in the German study, compared to a 56% detection rate for
mammography. Because DCIS often develops into invasive breast cancer, it is
almost always treated with surgery to remove all of the DCIS tissue.
The study appears in the Aug. 11 issue of the journal TheLancet.
In the U.S., magnetic resonance imaging (MRI) is currently recommended in
addition to an annual mammogram only for very high-risk women. But researcher
Christiane K. Kuhl, MD, of the University of Bonn, says the new findings could
mean a much broader use for breast MRI screening in the future.
"I would go so far as saying this is the beginning of the death of
mammography, but it is going to be a very, very slow death," Kuhl tells
"It will take many years before we have enough randomized prospective
trials to fully confirm our findings and enough radiologists who are qualified
to perform MRI to screen for breast cancer."
The Problems With MRI
Debbie Saslow, PhD, of the American Cancer Society, is unconvinced. She
tells WebMD that mammography is, and will remain, the screening tool of choice
for breast cancer for at least the next decade.
"We will see more technologies like MRI approved for use along with
mammography," she says. "But I don't know anyone who believes that any
of these technologies are candidates for replacing mammography."
Availability and cost are presently two important obstacles to a broader use
of breast MRI in the U.S., but they are not the only ones, Saslow says.
A breast MRI can cost $1,000 to $1,500 -- ten times the typical cost of
mammography. And there are currently not enough radiologists trained in the
procedure or dedicated breast MRI machines to provide screening to a larger
population of women.
But false positive results remain the biggest impediment to the use of
breast MRI in the screening of average-risk women, Saslow says.
The imaging technique is so sensitive that it finds many suspicious growths
that turn out not to be breast cancer (false positive), resulting in many
In the roughly 2% of American women who are considered to be at high risk
for breast cancer, the benefits of screening MRI outweigh these risks, but
Saslow says this is not true for most other women.
"For average-risk women, the harms of MRI outweigh the risks," she
says. "In addition, there have been no studies, including the current one,
which assessed MRI screening of women who were not at high risk."
Roughly one in six (29 of 167) of detected DCIS cases in the study by Kuhl
and colleagues occurred among average-risk women. The rest, Saslow points out,
occurred in women with a known elevated breast cancer risk.
Ninety-three were referred for MRI because of abnormal mammograms, 18 had
been treated for breast cancer, and eight had family history of the
"The women in the study were not representative of the population at
large, so it doesn't tell us much about the use of MRI in average-risk
women," she says.