left many unanswered questions

Boston, MA –July 1, 2004: In the past two years, the Women’s Health Initiative (WHI) trials of Premarin-based hormone therapy came to early ends because the risks outweighed the benefits. We now know that women 60 and older should not start taking hormone therapy, as they did in the WHI, to prevent heart disease. But what if a woman were to begin therapy earlier, during perimenopause, for example? Would the risks be the same? The July issue of the Harvard Women’s Health Watch asks these and other questions about this once widely-accepted treatment for postmenopausal ills.

Before the WHI, doctors observed that postmenopausal women taking hormone therapy had a 35%-50% reduction in heart disease. Laboratory animals treated with estrogen had clearer coronary arteries, and other studies suggested that estrogen improved cholesterol levels and blood vessel function. That’s why it seemed to make sense to encourage women in their fifties and older to take hormone therapy — that is, until 2002, when the WHI found that estrogen (Premarin) plus a progestin increased the risk of heart attack and stroke, as well as breast cancer.

Attention then turned to the WHI’s trial of estrogen (Premarin) alone vs. a placebo in more than 10,000 postmenopausal women with an average age of 63. That trial also came to a premature halt, because of a nearly 40% increased stroke risk in the estrogen-takers. Interestingly, Premarin alone did not increase heart disease risk, and it slightly lowered breast cancer risk. 

The July issue of Harvard Women’s Health Watch notes that the women involved in the estrogen-only arm of the WHI were older than the average woman who takes hormone therapy. Could this have skewed results? What about if the studies had used different preparations, doses, or applications of the medications? The July issue reports that researchers, including a Harvard Women’s Health Watch advisory board member, are starting a new trial to answer some of these questions.

The Harvard Women’s Health Watch is available from Harvard Health Publications, the publishing division of the Harvard Medical School. You can subscribe to Harvard Women’s Health Watch for $24 per year -877-649-9457 toll-free.