A reappraisal of the NIH Women's Health Initiative study has found that "the age when women start hormone replacement therapy makes a huge difference," in risk of cancer and heart disease, according to Dr. Robert Langer, lead author of the reassessment.
Researchers said "mass fear" left millions of women to needlessly suffer from menopause symptoms without the benefits of hormone replacement therapy after researchers halted the 2002 WHI study three years early because of the believed increased risk.
New data showed that the risks only apply to older menopausal women who begin taking the medication late into menopause.
"The balance is towards benefit for women with hot flashes and other reasons to use it who start within 10 years of menopause," said Langer. "But it's not beneficial for most women who start about 10 years or more into menopause."
Prior to the 2002 study, some research found that the menopausal hormone therapy actually helped to decrease the risk of heart disease, but the 2002 preliminary data found the treatment did not decrease risk and put women at increased risk of some invasive breast cancers and stroke. Prior to the study results, hormones were one of the most-prescribed drugs in the country.
But the use of estrogen dropped by 71 percent from 2001 to 2009, according to the North American Menopause Society.
"Women with a uterus who are currently taking estrogen plus progestin should have a serious talk with their doctor to see if they should continue it," Dr. Jacques Rossouw, acting director of the WHI at the time, explained in 2002. "If they are taking this hormone combination for short-term relief of symptoms, it may be reasonable to continue since the benefits are likely to outweigh the risks. Longer-term use or use for disease prevention must be re-evaluated given the multiple adverse effects noted in WHI."
For some women, menopause symptoms are much more than the occasional hot flash. Depression, low libido, night sweats, panic attacks and vaginal dryness are only a few of the many indications that storm through the body of a menopausal woman.
Symptoms like vaginal dryness and pain on intercourse are more difficult to bring up with a gynecologist than risks of heart disease and breast cancer, said Langer.
"Fears like the risk of breast cancer, or sometimes heart attacks or strokes, surface quickly in those discussions," continued Langer. "The reporting of the WHI fed those fears to a degree not warranted by the small increase in breast cancer rates that probably only reflected earlier discovery of existing cancers, or by the fact that the heart attack risk and stroke was only seen in women who started more than 10 years after menopause."
Currently, women are advised to use hormone therapy for as little time as possible and to stay on it no more than five years.
"I agree that for many younger menopausal women the quality of life issues helped by hormone therapy are large and that risk of relatively short-term use is small," said Dr. Ethel Siris, professor of clinical medicine at Columbia University Medical Center. "While on it, there is good bone protection, but once it is stopped, bone loss will rapidly occur so other bone protection may be needed later on."
Dr. Marcia Stefanick, a researcher on the WHI study, told ABCNews.com in March that the questions the initiative set out to answer were not specifically on menopause, but about the health risks and benefits of menopausal hormones for older women, "for whom they were being prescribed to prevent common diseases of aging women,' (i.e. heart disease, osteoporosis and dementia).
But Langer said overgeneralizing the results from the women who were about 12 years past menopause to all postmenopausal women led to needless suffering and lost opportunities for many.
"Sadly, one of the lessons from the WHI is that starting hormone therapy 10 years or more after menopause may not be a good idea, so the women who were scared away by the WHI over this past decade may have lost the opportunity to obtain the potential benefits," Langer said.