The recommendations concern only chronic disease, not the use of hormone therapy for reducing symptoms of menopause, such as hot flashes.
For the update, Nelson and her team looked at 51 published articles, involving nine research trials, that met their criteria.
They confirmed that both estrogen alone and combination therapy reduce the risk of fractures, as found before. But they concluded that both types of treatment increase the risk of stroke, blood clots, gallbladder disease and urinary incontinence.
While estrogen alone seems to reduces the risk of breast cancer, they found stronger evidence than before that combination therapy increases the risk for breast cancer. For every 10,000 women, eight more cases of breast cancer per year are expected in those on combination therapy, Nelson said.
Women who smoke, used birth control pills or took combination therapy for symptoms of menopause have higher risks of breast cancer, they found.
Estrogen-only therapy appears to reduce invasive breast cancer by about the same amount, she said, but cautioned that it's not a reason for taking it. This effect is stronger than before, Nelson said.
Other changes: Initial results indicated that those on combination therapy had a significant increased risk for heart disease. Now, that association appears weaker, she said.
Previously, the estrogen-progestin combination was thought to protect against colon cancer. That link also looks weaker, she said.
Nelson said the differences in risks and benefits are probably explained more by the risk profiles of the women who take each therapy rather than the progestin or its lack in the therapy itself. The women have different risk factors to begin with, she said. For instance, many taking only estrogen have had a hysterectomy, with their
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