Combination HT results in more unnecessary mammograms

Women who are prescribed combined hormone therapy are more likely to undergo otherwise avoidable mammograms and breast biopsies, according to a report published in the Feb. 25 issue of the Archives of Internal Medicine.

Rowan T. Chlebowski, MD, PhD, of Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center in Torrance, CA., and colleagues conducted a study of 16,608 postmenopausal women who were randomized to receive either 0.625 mg/d of equine estrogens plus 2.5 mg/d of medroxyprogesterone acetate or a placebo.

During 5.6 years of intervention, there was a 35% increase in the cumulative frequency of mammograms with abnormalities in the HT group versus 23% for the placebo group. The HT group had a higher incidence of breast cancer but biopsies from that group diagnosed cancer in only 14.8% of cases versus 19.6% for the placebo group.

“The higher frequency of mammograms with abnormalities continued even after the discontinuation of hormone therapy. The usable, quantitative estimates of the adverse effect of conjugated equine estrogens plus medroxyprogesterone acetate on breast cancer detection provided in this article should be incorporated into risk-benefit discussions with women considering even short-term use,” the authors conclude. “Clinical strategies to abrogate these problems have not been established but represent a research priority.” (The study authors report financial ties to the pharmaceutical industry.)

Chlebowski RT, Anderson G, Pettinger M, et al. Estrogen plus progestin and breast cancer detection by means of mammography and breast biopsy. Arch Intern Med. 2008;168:370-377.