Studies have focused on women too far past menopause to see any such benefit, these researchers say, so they plan to study women ages 40 to 55 whose last menstrual period occurred six months to three years earlier. Kronos Longevity Research Institute, a nonprofit organisation in Phoenix, will announce the eight US medical centres that will participate in the Kronos Early Estrogen Prevention Study. The study, which will involve 720 women, wonâ€™t begin enrolling them until at least September, but it has already spurred debate. The women will be randomly assigned to get estrogen or a placebo for five years. If they get estrogen, theyâ€™ll also get progesterone to protect their uterus from estrogenâ€™s cancer-causing effect. Because of its small size, the study will look only at indicators of heart disease risk, such as cholesterol levels and calcium deposits in coronary arteries.
Heart disease is so uncommon in women 40 to 55 that researchers would have to enroll tens of thousands and follow them for years to determine whether estrogen actually protects against it. In comparison, the government-sponsored Womenâ€™s Health Initiative (WHI) trial of estrogen plus progestin enrolled more than 16,000 women, while its trial of estrogen alone enrolled more than 10,000. The WHI reported that, after seven years of use on average, estrogen provided no heart benefit.
Earlier, the study showed that estrogen plus progestin raised the risk of heart attack. WHI participants were ages 50 to 79 and were 63 on average. â€œThere are still some real questions about recently menopausal women,â€ says JoAnn Manson of Bostonâ€™s Brigham and Womenâ€™s Hospital, a researcher with both the WHI and Kronos studies. â€œWomen are going to continue to use estrogen for the treatment of moderate to severe hot flashes. The more information they have to make an informed decision, the better.â€ But Deborah Grady, a menopause expert at the University of California-San Francisco who is not involved in either study, questions whether the latest study will provide useful information. Even if women using estrogen end up with better cholesterol levels and reduced calcium in their arteries, that doesnâ€™t mean theyâ€™re less likely to have a heart attack, she says.