Postmenopausal Hormones: Relative Risks

The next issue of The Medical Letter (October 14, 2013) will include an addendum to an earlier article (July 8, 2013) on the oral estrogen agonist/antagonist ospemifene (Osphena), which was approved by the FDA for treatment of postmenopausal dyspareunia. The reason for the addendum was that 2 readers objected in some detail to our recommendation that women with an intact uterus take a progestin. Unopposed estrogens increase the risk of endometrial cancer. Adding a progestin eliminates that risk, but increases the incidence of invasive breast cancer and cardiovascular disease. Whether ospemifene should qualify as an estrogenic agonist in endometrial tissue is the subject of some dispute, but the FDA says it does.

As it happens, just as we were preparing our addendum for publication, The Journal of the American Medical Association published an article (October 2) updating the results of the Women’s Health Initiative (WHI), which sponsored randomized placebo-controlled trials that are the source of the best information we have on the risks and benefits of postmenopausal hormones. The WHI did not compare estrogen plus a progestin with unopposed estrogen directly because the risk of endometrial cancer with the latter was already well known. Rather, they limited the trial of unopposed estrogen to women who had had a hysterectomy and compared both treatments with placebo.

For every 10,000 women who took estrogen plus a progestin for a median of 5.6 years, the WHI calculated that, compared to placebo, there were 9 more cases of breast cancer, 6 more coronary events, and 9 more strokes. The National Cancer Institute estimates that women with an intact uterus who take unopposed estrogen have a 10-fold increased risk of developing endometrial cancer. Relief from the symptoms of postmenopausal vaginal atrophy is not easily quantifiable. So where does that leave us in advising our patients? We will try to help answer that in our addendum. Coming soon.

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