Boston, MA- The Women's Health Initiative (WHI) hormone therapy trials tested the most common formulations of hormone therapy - estrogen and progestin, and estrogen alone - to assess the benefits and risks of menopausal hormone therapy taken for chronic disease prevention, by predominantly healthy postmenopausal women.
More breast cancer, heart attacks and strokes occurred in women on combined pills, and those on estrogen pills had more strokes.
Lichtenfeld brought up another point: Women on hormone therapy may not be more likely to die from cancer or heart disease because doctors have gotten better at treating those diseases, he said. These findings provide support for clinical guidelines endorsing the use of hormone therapy for recently menopausal women to manage bothersome hot flashes and other menopausal symptoms.
Hormone therapy is known to be effective in reducing hot flashes and menopausal symptoms, and decreasing the risk of hip and other fractures, but it has been also linked to risks including venous blood clots, stroke, and certain cancers.
The evidence comes from about 18 years of data on women involved in landmark research that transformed thinking on hormone benefits.
"It's the ultimate bottom line, ' said Manson, who was also part of the original research".
Brands studied were Prempro estrogen-progestin pills and Premarin estrogen-only pills.
"This study does not mean that a woman can nonchalantly start hormone therapy and stay on it for the rest of her life", he said.
The findings were published Tuesday in the US journal JAMA.
The landmark research, backed by the US government, began in the early 1990s to rigorously test hormones' effects in older women randomly assigned to take the pills or dummy treatment.
Women who took estrogen for an average of seven years or combination estrogen and progesterone therapy for an average of five years had no increased risk of death after 18 years of follow-up, compared with women given an inactive placebo, the researchers found.
Manson said the lack of impact on death rate from any cause is more important than the findings associated with death rate from cancer or heart disease.
Overall, nearly 7,500 women died - about 27 percent each in the hormone and dummy pill groups.
However, among women who initiated hormone therapy in their 60s and 70s, no effect on death rate was observed. The women took the hormone therapy for five to seven years. Hormone therapy is no longer widely recommended to prevent chronic disease like osteoporosis, heart disease or cancer, as they previously were.
More research is needed on risks and benefits of other types of hormones including patches, Mason said.