For women weighing whether to use estrogen to manage hot flashes, sleep issues and other bothersome symptoms as menopause approaches, it may make sense not to wait.

New research shows that perimenopausal women who had used estrogen for at least 10 years before their periods stopped for good had 60% lower odds for breast cancer, heart attack and stroke, compared to women who never took hormones.

The findings were scheduled for presentation at a meeting of The Menopause Society in Orlando, Florida, which continues through Saturday.

"There has long been a debate about if and when estrogen therapy should begin, so hopefully the use of large-scale electronic health record data will help resolve that question," lead author Ify Chidi of Case Western Reserve University School of Medicine in Cleveland said in a news release. "Hopefully, these results start a larger conversation about prevention in women’s health."

As menopause — the end of a woman’s menstrual periods — approaches, a large percentage of women experience annoying symptoms. Hot flashes and sleep disturbances are common during this transition, which is called perimenopause.

And, perimenopause can last for several years, as hormone levels wax and wane. 

While estrogen therapy, once controversial, has been shown effective and safe, according to The Menopause Society, long-term data about when to begin has been lacking.

For the study, Chidi’s team analyzed records from more than 120 million patients. 

They included women who used estrogen for at least 10 years before menopause; menopausal women currently using the hormone; and menopausal women not using estrogen.

The study found that women who waited until after menopause to begin estrogen therapy had slightly lower odds of breast cancer and heart attack than those who never took hormones. 

But they also had a 4.9% higher likelihood of having a stroke than the non-estrogen group.

"The findings of this study suggest lower risk and potentially greater benefit of estrogen-based therapy when started in perimenopause," Dr. Stephanie Faubion, medical director for The Menopause Society, said in a news release. 

She noted that the study’s design may be subject to bias, but added that the findings "may pave the way for additional research on the risks and benefits of hormone therapy when initiated earlier in the menopause transition."

Clinical research is needed to confirm the findings and to explore the long-term effects of estrogen therapy at different stages of menopause.

Research presented at meetings should be considered preliminary until published in a peer-reviewed journal.