Dense breasts have less fat and more non-fat tissue compared to breasts that aren't dense. Mammograms of dense breasts can be harder to read accurately. Hormone replacement therapy (HRT) can make some women's breasts denser. Doctors sometimes recommend stopping HRT a month or two before a mammogram, hoping that the mammogram can be read more accurately. A study found that stopping HRT before a mammogram didn't improve the accuracy of the mammogram reading.
Mammograms are probably the most important tool used to diagnose breast cancer. While safe and generally quite accurate, mammograms aren't perfect. When a mammogram identifies an abnormality that looks like a cancer but turns out to be normal, it's called a false positive. Ultimately the news is good: no breast cancer. But false positives do cause psychological stress, extra tests and procedures, and additional follow-up visits with a doctor.
Getting a false positive result from a mammogram is more likely in women with dense breasts. Since HRT tends to increase breast density, women using HRT are more likely to get a false positive mammogram result.
This study, called the Radiological Evaluation and Breast Density (READ) trial, looked at more than 1,700 women between the ages of 45 and 80 who were taking HRT to ease menopausal symptoms:
- one-third of the women kept taking HRT before getting an annual mammogram
- one third of the women stopped HRT 1 month before an annual mammogram
- one-third of the women stopped HRT 2 months before an annual mammogram
The researchers found that the risk of false positive mammogram results were the same for all three groups of women. So stopping HRT before the mammogram didn't improve the accuracy of the mammogram.
- 11.3% of the women who didn't stop HRT had a false-positive reading
- 12.3% of the women who stopped HRT 1 month before the mammogram had a false positive reading
- 9.8% of the women who stopped HRT 2 months before the mammogram had a false positive reading
The differences in the false positive rates weren't statistically significant, which means they could have been the result of chance and not because of stopping HRT.
The researchers did find that women who stopped taking HRT before getting a mammogram had less dense breasts than women who didn't stop HRT. Still, women who stopped taking HRT tended to have more menopausal symptoms compared to women who kept taking HRT.
If you're taking HRT to ease menopausal symptoms, your doctor may recommend that you stop taking HRT before getting your annual mammogram. If so, you might consider talking about this study with your doctor. Based on these results, stopping HRT may not make your mammogram reading more accurate and you may have more menopausal symptoms.
Taking HRT is one way to deal with menopausal symptoms, but HRT can increase the risk of breast cancer. Visit the Breastcancer.org Managing Menopausal Symptoms section for information on menopausal symptoms and ways to manage them.