Fifteen years after a major study suggested that hormone replacement therapy put menopausal women’s health at risk, follow-up research has found that the hormones did not increase premature deaths.   

A long-term follow-up of more than 27,000 women who were part of the Women’s Health Initiative found no link between hormone therapies used in the landmark study and deaths from cardiovascular disease, cancer or other major illnesses.

The Women’s Health Initiative (WHI) study looked at the effects of estrogen-only and estrogen-progestin combination therapies used in menopausal women to prevent age-related diseases. The study was halted in 2002, after investigators found the hormone therapy appeared to put women at greater risk of invasive breast cancer, strokes and heart disease.

The findings left women fearful of hormone replacement therapy, with many of them choosing to instead suffer through hot flashes, mood changes and sleep problems, along with other symptoms of menopause.

However, an 18-year follow-up of 27,347 women who were part of the WHI study found that they were no more likely to die of any cause than women who took placebo pills.

The study, published in the journal JAMA, is the first to examine long-term death rates from all causes among women who received the hormone therapies.

While the study found no overall increase or decrease in death rates among women between the ages of 50 and 79, the mortality rates were lowest among younger women in the group (aged 50 to 59).

"Mortality rates are the ultimate 'bottom line' when assessing the net effect of a medication on serious and life-threatening health outcomes," Dr. JoAnn Manson, the study’s lead author, said in a news release.

The researchers say their findings support the use of hormone therapy for recently menopausal women to treat hot flashes and other symptoms. But there is no evidence that hormone therapy should be used for prevention of cardiovascular diseases and other chronic illnesses, they say.

CTV News’ medical expert Dr. Marla Shapiro said the latest study is “very reassuring for women” who have been afraid of trying hormone therapy.

She said the findings suggest it’s safe for women between the ages of 50 and 60 to try hormone therapy for treatment of menopause symptoms, but not for chronic disease prevention.

“What it basically tells us is that individualization of treatment remains critical,” Dr. Shapiro told CTV News Channel Tuesday. “We now think about an appropriate dose for the appropriate length of time for the appropriate woman dealing with the (menopause) symptoms that she has.”

Both Dr. Shapiro and the Boston researchers note that the latest study examined the effects of hormone therapies used many years ago, at the start of the WHI study.

Today, there are new formulations of hormone therapies, which include lower doses and novel administration methods, such as skin patches, gels, and sprays.

More research is necessary on the long-term benefits and risks of newer hormone therapies, the researchers say.