Can Hormone Replacement Therapy Compromise a Mammogram's Accuracy?
Still, she says women taking HRT or who are considering starting it should discuss the issue with their doctors.
Zaslow agrees. "Hopefully, her doctor or radiologist will let her know, and that is one more reason why she should get her mammogram every year."
The study's authors, led by Carolyn M. Rutter, PhD, say compared with women who did not take HRT, women who did were significantly more likely to have increases in the density of their breasts. The study also found differences in individual women's responses to HRT. For instance, the probability of an increase in tissue density while taking HRT increased with increasing age.
However, Rutter, a researcher with Group Health Cooperative's Center for Health Studies in Seattle, also found that women who stopped taking HRT during the study had decreases in breast tissue thickness, suggesting that the effect of HRT may be temporary and reversible.
A similar study presented last month at a radiology meeting by researchers from Germany found that HRT also compromises the accuracy of breast MRI scans, which are occasionally used after a woman has had a suspicious finding on a standard mammogram. The German researchers say the problem is so significant they believe women should actually consider stopping their hormone therapy a few weeks prior to having an MRI to reduce the risk of either missing a cancer that is hidden by increased breast tissue or detecting something that looks like a tumor but is only an increased mass of normal breast tissue.
But Zaslow says while the suggestion to stop HRT before having a breast scan may be reasonable in some cases under doctor supervision, it still needs to be studied further. For now, the women taking HRT should not stop therapy without talking first with their doctor to determine if the benefits of the therapy outweigh any potential risk.
"Women need to talk to their doctors about why they're taking HRT. If they're taking it for severe hot flashes and it's helping them, that may be more important than a slight possible decrease in their mammogram sensitivity," she says.