Reevaluating Hormone Replacement Therapy

Just last week, Manson and her colleagues reported in the New England Journal of Medicine that women in their 50s who take estrogen therapy have lower levels of dangerous calcium deposits in their arteries, suggesting they're at reduced risk for heart disease.

But in older women, hormone therapy appears to increase the risk of cardiovascular problems and blood clots, a phenomenon confirmed by a study in this week's British Medical Journal.

And researchers have speculated that a decline in the incidence of breast cancer in recent years is due to a decline in the use of hormone therapy after the WHI results were announced. But a cause-and-effect link is not at all clear.

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"I think it's possible that declining use of hormone therapy has contributed at least a little to a decreased incidence rate, but there could be other explanations," Manson said. "There's some suggestion that the decline in breast cancer may have begun as early as 1999, which was well before there was decreasing use of hormone therapy. And there is also some evidence that mammogram screening has decreased over the past several years and that this could contribute to lower rates of detection and diagnosis of breast cancer."

That being said, combined estrogen and progestin has been linked to a risk of breast cancer after four to five years of use. It's not clear if estrogen has a similar risk.

There was some evidence in the WHI study that combination hormone therapy reduced the risk of colon cancer, but the evidence isn't enough to recommend hormones as a preventive strategy, Manson said.

Similarly, while estrogen reduces the risk of fracture and enhances bone density, this benefit would require long-term treatment. Other medications are available and should be tried first, Manson said.

Overall, the bulk of the research today, five years after the WHI, should serve to reassure younger women who may need hormone therapy to alleviate menopausal symptoms.

"The most important reason to go on hormone therapy is for menopausal symptoms," said Dr. Nieca Goldberg, medical director of the Women's Health Program at New York University Medical Center and associate professor of medicine at New York University School of Medicine. "Younger women who need to go on hormone therapy for this reason can relax. But hormone therapy should never be given to women with cardiovascular disease."