MONDAY, Feb. 25, 2008 (HealthDay News) -- Women who take combined hormone therapy for about five years have a higher risk of abnormal mammograms and breast biopsies.
This, in turn, may decrease the effectiveness of these methods of detecting breast cancer, according to a new study published in the Feb. 25 issue of Archives of Internal Medicine.
"Women need to be aware of the risks, and it's not just risk of increased breast cancer. It's a risk of possibly having abnormal mammograms and really being tortured by them," said Dr. Kristin Byrne, chief of breast imaging at Lenox Hill Hospital in New York City, who was not involved with the study. "It's a whole slew of things they need to be aware of before making a decision to go on hormone therapy."
Study lead author Dr. Rowan Chlebowski, a medical oncologist with the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, said that for women with severe menopausal symptoms, the new findings "won't be an issue."
"It [hormone-replacement therapy] is safer than we thought maybe a year and a half ago," he said. "Certainly, no one is going to brush off a breast biopsy. But for women trying to decide whether to start on hormone therapy or who want to see if their symptoms get better, they have to think about whether they would mind having a call back" for a mammogram.
The landmark Women's Health Initiative (WHI) study found that combined estrogen plus progestin hormone replacement therapy (HRT) increased the risk of breast cancer. One recent study indicated that the risk was greater for lobular breast cancer than ductal carcinoma malignancy.
Since 2003, there has been a decline in breast cancer incidence that coincided with a decline in HRT use for menopausal symptoms. Nevertheless, Chlebowski pointed out, "a lot of people are still using hormone therapy."
For the new study, the authors looked at 16,608 women who participated in the WHI from 1993 to 1998. The women were randomly assigned to receive combined hormone replacement therapy (estrogen plus progesterone) or a placebo.
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.
