November 2008

HT linked to abnormal mammograms

Combined hormone therapy appears to increase the risk that women will have abnormal mammograms and breast biopsies and may decrease the effectiveness of both methods for detecting breast cancer, according to a report in the Archives of Internal Medicine, one of the JAMA/Archives journals, earlier this year.

Hormone therapy use remains common among women beginning menopause, according to background information in the article. "For women with a uterus considering combined estrogen plus progestin use, identified breast cancer issues represent a concern," the authors wrote.

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% vs. 23%); women taking hormones had a four percent greater risk of having a mammogram with abnormalities after one year and an eleven percent greater risk after five years.

Breast biopsies also were more common among women taking hormones than among those assigned to placebo (10% vs. 6.1%). "Although breast cancers were significantly increased and were diagnosed at higher stages in the combined hormone group, biopsies in that group less frequently diagnosed cancer (14.8% vs. 19.6%)," the authors wrote.

"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," they said.

SOURCE: Archives of Internal Medicine, 2008;168[4]:370-377.