Post-menopausal women on hormone replacement are usually advised to stop taking their hormone therapy for 1-2 months before they have a mammogram to screen for breast cancer based on research that suggested that this would improve the quality of the mammogram. Hormone replacement therapy (HRT) makes the breast tissue appear more dense (thicker) so that it’s more difficult to examine the breast tissue properly. This leads to an increase in “false positive” results when doing a mammogram.
False positives are mammograms in which it looks like there is cancer present in the breast even though the breast is actually normal. If your mammogram looks abnormal in any way, you are usually asked to come back for a repeat mammogram. This can produce a lot of unnecessary anxiety in women who actually have nothing to be worried about.
New research has shown that temporarily stopping hormone therapy before a mammogram has no benefits in terms of reducing the number of false positeve results. Repeat mammograms for false positives contribute about 25% to the overall cost of mammograms to the U.S. government. An additional problem is that women are being exposed to additional x-rays which are potentially harmful to the body but which is necessary to confirm that they don’t actually have breast cancer. In spite of all the criticism of mammograms for breast cancer screening, right now this is the most effective, readily available way for women to get screened for breast cancer.