The study reviewed here found that women taking HRT (hormone replacement therapy) with both estrogen and progesterone -- called combination HRT -- were more likely to have an abnormal mammogram than women not taking combination HRT. Combination HRT also makes it harder for doctors to read annual screening mammograms. In other words, doctors have hard time deciding whether or not the mammogram shows breast cancer. Other research has shown that HRT increases breast cancer risk.
In this study, 35% of women taking combination HRT had an abnormal mammogram. In comparison, 23% of women who weren't taking combination HRT had an abnormal mammogram. The different rate of abnormal mammograms was found the whole time the women were taking combination HRT and continued for a year after they stopped taking it.
This study, called the Women's Health Initiative (WHI), is very large; thousands of women participated. Other results from the WHI have helped doctors understand the link between using HRT and increased breast cancer risk.
The researchers didn't explain why reading mammograms was harder in women taking combination HRT. It could be doctors were more suspicious and less confident of reading these mammograms because of the higher breast cancer risk associated with taking HRT.
If a screening mammogram is questionable, doctors usually order more testing, such as another mammogram or a biopsy, to help them figure out if cancer is present. Compared to women not taking HRT, women taking combination HRT were 35% more likely to get an extra mammogram and 23% more likely to have a breast biopsy because the initial mammogram had abnormal results.
Even though the initial mammogram was classified as abnormal, many of the women didn't have breast cancer. The researchers considered the additional tests "unnecessary," even though there were good reasons for them. By taking HRT for 5 years, the researchers estimated that a woman has a 10% risk of having an unnecessary mammogram and a 4% risk of having an unnecessary biopsy.
The side effects of menopause can dramatically reduce quality of life for some women. These women have to weigh the benefits of HRT against the risks. If you're having severe menopausal side effects and are considering HRT, talk to your doctor about how you can minimize your breast cancer risk. Be sure to discuss the pros and cons of different types of HRT. Estrogen-only HRT appears to increase breast cancer risk less than combination HRT. Based on the study reviewed here, you might want to ask your doctor about how HRT might affect the reliability of your routine mammograms and the potential need for follow-up testing.
If you do decide to take HRT, try to use it for the shortest time possible. One study found that breast cancer risk was not significantly increased when combination HRT was used for fewer than 3 years. Together, you and your doctor can decide if HRT or another treatment for menopause might be right for you.
NEW YORK (Reuters Health) - Detecting breast cancer with mammography and biopsy is more difficult in women who use estrogen and progestin hormone therapy, according to an analysis of data from the Women's Health Initiative (WHI) trial.
Doctors "should be aware that breast cancer diagnosis is more difficult in women using combined hormone therapy," lead researcher Dr. Rowan T. Chlebowski told Reuters Health. Such therapy has a considerable effect on the risks of having an otherwise avoidable mammogram or breast biopsy, he added.
Other studies have examined the impact of hormone replacement therapy on breast cancer detection, noted Chlebowski, a researcher with the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center in Torrance, California. However, unlike the current study, these studies generally did not examine how hormone therapy affects breast cancer detection over the course of treatment, he explained.
Because of this difference in study design, "we can provide, for the first time, precise...estimates of what a woman can expect if she uses estrogen plus progestin for about five years."
As reported in the Archives of Internal Medicine, the researchers analyzed data from 16,608 postmenopausal women who were randomly assigned to receive estrogen plus progestin or an inactive placebo as part of the WHI trial.
Mammography and breast examinations were performed at the start of the study and annually, and breast biopsies were performed according to the findings of these exams. The impact of hormone therapy on breast cancer detection was determined through 5.6 years of treatment.
Overall, 35 percent of mammograms in hormone users were considered abnormal compared with just 23 percent of those in placebo users. Most importantly, the mammograms performed in hormone users were less able to visualize breast cancer and resulted in more unnecessary biopsies.
Stopping hormone therapy improved breast cancer detection with mammography and breast biopsy, but the diagnostic ability was still inferior compared with that in women who had never used estrogen and progestin. The reduced ability to detect cancer persisted for at least 12 months after hormone therapy stopped.
Doctors should make their patients on combined hormone therapy aware that the risk of having an unnecessary mammogram or breast biopsy is "considerable," about 10 percent and 4 percent, respectively, over 5 years, Chlebowski noted.
SOURCE: Archives of Internal Medicine, February 25, 2008.
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