According to a new study hormone therapy may not be as risky for elder women as earlier thought. This comes from the Women's Health Initiative, a federally funded trial that tracked thousands of women taking hormones or placebo pills for years. The WHI looked at women who have had hysterectomies or have had their uterus removed and thus can take estrogen unaccompanied by another hormone, progestin. It found that a heightened risk of stroke from taking estrogen faded with time, while a reduced risk of breast cancer held steady.
This study was published Tuesday in the Journal of the American Medical Association (JAMA). The current recommendation from doctors that hormones to treat hot flashes and other menopausal symptoms should be taken in the smallest doses possible for the shortest amount of time may change with this study.
“This study is very good news for women without a uterus,” said Andrea LaCroix, the lead author of the study and an epidemiologist at the Fred Hutchinson Cancer Research Center in Seattle. In the WHI the estrogen-only arm which began with more than 10,000 women ages 50 to 79 who'd had hysterectomies, was halted prematurely in 2004 after researchers discovered that the risk of stroke was slightly higher. It was 12 more cases among 10,000 people in women who had taken estrogen for an average of six years compared with those who received placebo pills. At the same time, the hormone failed to reduce the risk of heart disease, which had been the principal hope of the study.
LaCroix and her colleagues examined data from 7,645 of the participants more than four years after they had stopped therapy. Women randomly assigned to take hormone therapy used Premarin, a hormone therapy made by Wyeth, a pharmaceutical company now owned by Pfizer. The scientists found that a slightly higher risk of blood clots in the legs, corresponding to six additional cases per 10,000 women, vanished along with the increased risk of stroke. So too did a benefit: A small decreased risk of hip fracture seen during the intervention with six fewer hip fractures per 10,000 women that returned to baseline after the women stopped taking estrogen.
“What's very interesting is the fact that the reduction of breast cancer in this particular group persisted while all the other risks and benefits disappeared,” said Dr. Margery Gass, executive director of the North American Menopause Society and a consultant at the Cleveland Clinic, who was not involved in this particular Women's Health Initiative report. “It's very hard to explain.”
Studies have shown that estrogen promotes breast cancer in some women by stimulating cell growth and inhibiting the natural suicide of cells, a process called apoptosis. “In these circumstances, estrogen acts like it stimulates apoptosis,” said Dr. Rowan T. Chlebowski, a medical oncologist at the Los Angeles Biomedical Research Institute and a coauthor of the study. By so doing, it could cause precancerous cells in the breast to self-destruct before they cause problems. He called the finding on breast cancer risk reduction “definitive.”
Most women were age 60 or older when the study began so the results reflect the effects of estrogen in the elderly women. In normal medical settings, women begin taking hormones for relief of symptoms such as hot flashes that occur at the time of menopause, which for most women is in their early 50s. The safety profile for the younger women appeared better than for older women in the study, LaCroix and her colleagues reported, “The younger women were less likely to have heart attacks or die from other diseases. Based on these findings, the scientists calculated that if 10,000 women ages 50 to 59 took estrogen for 10 years and seven months, there would be 12 fewer acute heart attacks, 13 fewer deaths from any cause and 18 fewer adverse events related to chronic diseases, such as diabetes, compared with women taking placebo pills. In contrast, in 10,000 women ages 70 to 79, there would be 16 more heart attacks, 19 more deaths and 48 more adverse events related to chronic diseases compared with women taking placebos.” “Six years of use followed by stopping appears to be very safe for younger women, with the exception of blood clots,” LaCroix said. “But for women in their 70s, this does not appear to be a safe medicine.”
In an editorial accompanying the study, researchers from Washington University School of Medicine in St. Louis feel this would not change the attitude towards hormones. Prescriptions have plummeted in the last seven years as hopes were dashed that hormone therapy would generally improve women's health in the later part of life. “Instead of women taking a pill they thought was going to protect against heart disease and osteoporosis and all these other effects, you now offer a pill that has benefits and risk that equal out,” said Dr. Graham Colditz, a co-author of the editorial. “Most people aren't going to run out to take something that may cause them to have a stroke.”
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