HRT Can Lead to Abnormal Mammograms, Biopsies

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Mammograms and breast exams were conducted annually and biopsies performed, if indicated.

More than one in 10 women had otherwise avoidable mammogram abnormalities (an increase of 11 percent), while one out of 25 women had otherwise avoidable breast biopsies (an increase of 4 percent), after taking the hormone therapy for five years.

Ten percent of women in the HRT group had to have a biopsy, compared to 6.1 percent in the placebo group. Yet the biopsies only detected 14.8 percent of cancers in the HRT group, compared with 19.6 percent in the placebo group.

"Your breasts become denser [with HRT], and we all know that mammography isn't as sensitive for the detection of breast cancer in women with dense breasts," Byrne explained.

The increase in abnormal mammograms persisted for at least 12 months even after discontinuing hormone therapy, the study found.

For the medical community, Chlebowski said, this finding "focuses attention that diagnosis is hindered. We have additional imaging modalities, and maybe we should evaluate them to see if we can get rid of this hindrance or delay in diagnosis. It hasn't been a factor for attention before, but it probably should be."

Chlebowski has consulted for several pharmaceutical companies.

A prepared statement from Wyeth Pharmaceuticals, which makes the hormonal product Prempro, said: "This study looks at data first reported in 2002 which showed an increase in the number of repeat mammograms and breast biopsies related to the use of estrogen combined with progestin. Current labeling for all hormone therapy products provides information about breast cancer risks, abnormal mammograms and guidance regarding yearly breast examinations by a healthcare professional.

"While use of estrogen combined with progestin increased the need for repeat mammograms in this study, nearly one in four women in the placebo group also needed repeat mammograms due to abnormalities. The findings in this report do not change what we already know about the benefits and risks of hormone therapy," the statement said.

More information

For more on the Women's Health Initiative, visit the U.S. National Heart, Lung, and Blood Institute.