September 15, 2010

HRT May Muddy Women's Mammograms

Hormone replacement therapy may affect how doctors interpret the tests, leading to diagnoses of breast cancer where none is present.

Studies have shown that the mammograms of women who are on hormone replacement therapy (HRT) during menopause may be harder for doctors to read than for those who have not taken hormones. This is because hormones seem to change the density of the breast tissue, making interpretation more difficult. A new study set out to explore this idea as well as determine whether the various types of HRT could affect the results differently.

The women on HRT had a 1.5% chance of getting false-positive reading, vs. 0.8% of women who had never taken hormones.

The research team followed almost 173,000 women who had mammograms over a period of about 14 years. The women on HRT took hormones orally, via a patch, or through injection. The women on HRT had a 1.5% chance of getting false-positive reading, vs. 0.8% of women who had never taken hormones. A false-positive means that the doctors thought they saw breast cancer when in fact there was none. Though the difference may not sound large, it was statistically significant, which means that it is not likely to be due to chance and that there is a real effect here.

When the researchers from the University of Copenhagen looked at how the different types of HRT measured up against one another, they found that women taking oral hormones had a lower risk of having a false-positive reading than women who used estrogen-progesterone patches or took estrogen injections. It’s not clear what the reason for this is, but previous studies have also suggested that the method by which the hormones are taken may have different effects on the breast tissue. More research will be needed to flesh out the differences in how the various methods affect the interpretation of mammograms and just why these differences occur in the first place.

In the meantime, women on HRT should not be afraid to have mammograms. It remains an effective method of screening for breast cancer. As always, it’s a good idea to discuss with your doctor any concerns you have about the treatment you’re currently taking or may take in the future.

The research was published in the August 19, 2010 online issue of Menopause.

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