Hormone Replacement Therapy and Breast MRI Don't Mix

Medically Reviewed by Pamela R. Yoder, MD, FACOG, PhD on December 06, 2000
From the WebMD Archives

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 breast.

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.