Despite the highly publicized closing of the Women's Health Initiative study, the scientific community should not rule out that women may benefit from hormone therapy after menopause, say researchers at UC Davis, Duke and Harvard universities. Their review of the scientific literature on the biology of estrogens and progestins appears in today's issue of the journal Science.

"It was right to close the Women's Health Initiative trial," said Judith Turgeon, professor of internal medicine at the UC Davis School of Medicine and senior author of the Science article. "But we should not generalize the results of this trial and overlook the real potential that other forms of hormone therapy may offer to postmenopausal women."

Women's Health Initiative trials used the steroid formulation most frequently prescribed in the United States at the time, given to women in daily pill form. New information gleaned from research in the biology of ovarian hormones, however, indicates that not all estrogens and progestins are alike, nor do they behave identically in different tissues in the body.

"As our understanding of the biology of these hormones grows, the more we realize how important certain factors are -- such as formulation, dosage, whether they're given by a pill or a patch, and characteristics of women being treated," said co-author Phyllis Wise, biological sciences dean and a professor of neurobiology, physiology and behavior. "More targeted therapies may yield important health benefits."

Estrogens affect many tissues in the body. During natural menopause, which occurs in women at an average age of 51 years, estrogen and progesterone secretions from the ovaries diminish. Afterward, the risk of coronary heart disease and osteoporosis increases. Stroke and dementia are also associated with aging.

"Estrogens and progestins provide women with important health advantages before menopause," Turgeon said. "We need to remain open to the possibility that these same ovarian hormones can help women stay healthier after menopause as well."

Hormone therapy was once thought to help postmenopausal women keep their health risks closer to levels seen in younger women. But prescribing such therapy was largely abandoned by physicians after the Women's Health Initiative clinical trials found in 2002 that women on combination estrogen and progestin had a slightly higher risk of heart attacks, strokes and blood clots. However, the study also found that the hormone therapy offered some protection against fractures and colon cancer.

"Estrogens are important to maintain normal brain function and may protect against neurodegeneration," said Wise, who has conducted numerous laboratory studies on the protective effect of estrogens on the brain during aging and after injury. "There are so many potential benefits of estrogens and progestins after menopause. Our goal is to find the right formulation and circumstances that will enable us to retain health benefits, while eliminating the risks."