June 2008

Hormone therapy may pose health 'concern'

Women who receive combined hormone therapy may be at an increased risk of abnormal mammograms and breast biopsies according to a report in the Feb. 25 issue of Archives of Internal Medicine. In addition, the drugs may decrease the effectiveness of both methods for detecting breast cancer.

Hormone therapy use remains common among women beginning menopause, according to background information in the article. The researchers pointed out that the increased risk represents a health "concern" for most women considering combined estrogen plus progestin.

Rowan T. Chlebowski, MD, PhD, of the Los Angeles Biomedical Research Institute at Harbor - UCLA Medical Center, and colleagues studied 16,608 post-menopausal women who participated in the Women's Health Initiative (WHI) clinical trial, beginning in 1993 through 1998.

A total of 8,506 women were randomly assigned to receive a combination of estrogen (0.625 milligrams of conjugated equine estrogens per day) plus progesterone (2.5 milligrams of medroxyprogesterone acetate per day), while 8,102 took a placebo. Each woman received a mammogram and breast examination yearly, with biopsies performed based on physicians' clinical judgment.

During the 5.6 years of the study, 199 women in the combined hormone group and 150 women in the placebo group developed breast cancer. Mammograms with abnormal results were more common among women taking hormones than among women taking placebo (35 percent vs. 23 percent); women taking hormones had a four percent greater risk of having a mammogram with abnormalities after one year and an 11 percent greater risk after five years.

Breast biopsies also were more common among women taking hormones than among those assigned to placebo (10 percent vs. 6.1 percent). "After discontinuation of combined hormone therapy, its adverse effect on mammograms modulated but remained significantly different from that of placebo for at least 12 months," the report noted.