Hormone Replacement Therapy and Breast MRI Don't Mix
Dec. 6, 2000 (Chicago) -- If a woman's mammogram raises
suspicion, her doctor may have her get an MRI scan of the breast for a better
look. Unfortunately, many postmenopausal women may be counteracting these extra
efforts. How? By taking hormone replacement therapy.
In research presented at a radiology meeting here, researchers
say hormone replacement therapy makes breast tissue appear brighter on the
sophisticated MRI tests and they may therefore have a harder time interpreting
test results. These enhancements don't show up on standard mammograms and the
problem is most likely to occur in women taking hormones that include
progesterone, they found.
The researchers say that stopping hormone therapy for a period
before an MRI will give doctors a better view of potential problems in the
Still, "no patient should stop taking hormones without
consulting their doctor," says researcher Christiane Kuhl, MD, associate
professor of radiology at the University of Bonn in Germany. But she recommends
women stop taking hormones for about four weeks before a planned MRI.
If a woman has suspicious areas on a mammogram and MRI shows
enhancement in the same area, Kuhl recommends a biopsy where a sample of breast
tissue is taken for further testing. "However, if that MRI showed
enhancement in other areas, I think it would be prudent to ask the woman to
stop hormones and then return for another study," she says.
In her study, Kuhl recruited 62 healthy women who had either
not entered menopause, were postmenopausal but did not use hormone replacement,
and postmenopausal women who did take hormone replacement. Women in the
third group went through two series of MRIs and then were asked to stop taking
hormones and take a third examination four weeks later.
Those who had the most suspicious areas in the breast as seen
with MRI were those who were on hormones. After they stopped taking them,
however, 92% of their test results were given a thumbs up.
"This is very important data," says Laura Liberman, MD,
of Memorial Sloan-Kettering Cancer Center in New York. "It was really
helpful to show the reversal effect by stopping hormones. I think there might
be enough evidence to recommend stopping hormones for four to six weeks and
then repeating the MRI study."
Markus Mueller-Schimpfle, MD, associate professor of radiology
at University Hospital in Tuebingen, Germany, points out that hormone treatment
not only can enhance a normal image to the point that it becomes suspicious,
but it can also mask dangerous cancers.
And he agrees with Kuhl and Liberman. "Absolutely, I would
have a women stop hormones if she were coming in for a diagnostic MRI scan. We
can see the effect in a short time -- about four weeks," he says.
Why hormones cause the enhancement is still a bit of a mystery,
adds Hedvig Hricak, MD, chairman of the department of radiology at Memorial
Sloan-Kettering. But "we think there is a role being played by progestin,
one of the hormones usually taken by women on hormone replacement therapy,"
she tells WebMD.