(CBS) Researchers estimate that about 50,000 deaths could have been prevented if women who had hysterectomies took estrogen hormonal therapy.
"Estrogen avoidance has resulted in a real cost in women's lives every year for the last 10 years -- and the deaths continue," Dr. Philip Sarrel, emeritus professor in the Departments of Obstetrics, Gynecology & Reproductive Sciences, and Psychiatry at Yale School of Medicine, said in a press release. "We hope this article will stir an overdue debate and raise consciousness about the health benefits of estrogen-only therapy for women in their 50s with no uterus."
The study was published on July 18 in the American Journal of Public Health.
After the 2002 Women's Health Initiative (WHI) study, patients and doctors became wary of using estrogen therapy. The WHI was 15-year study involving post-menopausal women between 50 and 79, who were enrolled in clinical trials of hormone therapy, dietary modification and taking calcium/vitamin D supplements. More than 160,000 women were involved in at least one of the three portions of the study.
The study found that an estrogen-progestin combination therapy was shown to increase the risk of breast cancer, heart disease, stroke and blood clots in women compared to those took a placebo.
The study caused fewer women to turn to estrogen therapy.
Before 2002, more than 90 percent of women used the hormone to treat menopausal symptoms like hot flashes and to prevent osteoporosis and other diseases, the researchers reported. Today, only 10 percent of women use estrogen.
The researchers behind the new study point out, however, that most of the negative health outcomes in the earlier trials were seen in women who still had their uterus and took a combination estrogen-progestin pill to lower the risk of uterine cancer.
Because of this, the researchers believed that many of the negative results did not apply to women who had a hysterectomy, or had their uterus removed, and could benefit from estrogen alone.
"Sadly, the media, women, and health care providers did not appreciate the difference between the two kinds of hormone therapy," Sarrel said. "As a result, the use of all forms of FDA-approved menopausal hormone therapy declined precipitously."
The researchers looked closely at another part of the WHI study, which looked at women 50 through 59 who did not have a uterus and who took estrogen-only or placebo therapy. They discovered more positive health outcomes. Data from 2011 and 2012 showed that women without a uterus who took estrogen had fewer deaths each year over 10 years and were less likely to develop breast cancer and heart disease.
Taking estrogen-only therapy was shown to reduce the risk of invasive breast cancer by 20 percent, and a 2011 study showed reduction in overall breast caner by 60 percent. In addition, women who took the placebo had 13 more deaths per 10,000 people compared to women on estrogen.
Dr. Holly L. Thacker, director at the Center for Specialized Women's Health at Cleveland Clinic, said to CBS News, said that the research shows that doctors and patients need to re-look at estrogen, not just as a treatment, but as a possible prevention therapy. She was happy to see people were still looking into it. Estrogen has been shown to lower risk for heart disease and osteoporosis. The doctor added that she believed women who are within 10 years of menopause may have the most to gain from estrogen therapy.
"Women should not be afraid of estrogen and for many women it can have a beneficial effect on both quality of life and longevity," she said.
At the same time, Thacker said it's hard to ignore the fact that oral estrogen has been linked to increased risk for blood clots.
One researcher, however, cautioned that people should be wary of these results.
"This is another one of those highly theoretical papers, based on complex mathematical analyses that are also quite indirect," Dr. Freya R. Schnabel, director of breast surgery at NYU Langone Medical Center, said to CBS News.
Schnabel pointed out that the researchers came up with the 50,000 figure by estimating the number of women who have had hysterectomies and how many of them would have died based on the calculated reduction in deaths from heart disease. However, they do not factor in if many of these women had heart disease before they entered the study or if they were low risk to begin with, she said.
The authors also focused on the benefits among the 50 to 59 group, she said, but not why it doesn't benefit women ages 60 to 69 years old.
"I am not impressed that they have made their case -- I think this is a highly artificial study, and the conclusions, which are not nuanced in the slightest, are a real stretch," said Schnabel.
© 2013 CBS Interactive Inc. All Rights Reserved.