Last Updated: 2003-08-26 16:00:27 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Treatment with ultra-low doses of estrogen appears to be safe and to increase bone density in older women, according to a new report.

Many doctors have abandoned hormone replacement therapy after a study released last year indicated that it may promote breast cancer and heart disease. But it could still have a place, Dr. Karen M. Prestwood told Reuters Health.

"I do believe there is still a role for estrogen replacement therapy in some women and it may be that using the lower dose is the way to go," said the author of the latest study, published in the Journal of the American Medical Association.

Prestwood's team studied 167 older women who were randomly given an inactive placebo drug or 0.25 milligrams of estradiol (a type of estrogen) to take daily for three years. All of the women who had not had a hysterectomy were also given 100 milligrams of oral progesterone daily for two weeks every six months.

Compared with placebo, estrogen treatment produced a significant increase in bone mineral density (BMD), the researchers found.

Patients treated with ultra-low-dose estrogen were no more likely than those given a placebo to experience breast tenderness, a problem often seen with conventional-dose estrogen. In addition, there was no sign that estrogen therapy caused tissue changes that could lead to endometrial or breast cancer.

"As far as I know, there have been no published studies looking at an estrogen dose as low as we used--at least not for as long a period of time," said Prestwood, from the University of Connecticut Health Center in Farmington.

"Early on in my geriatrics practice, I noticed that a lot of women just didn't tolerate conventional-dose estrogen. So, I became interested in lowering the dose," she explained

Even with lower and lower doses over the years, "I still haven't found an estrogen dose without some benefit to bone," Prestwood noted.

This suggests that there could be a level of estrogen replacement that strengthens bone, but does not promote breast cancer or the other adverse effects seen in other studies, she added.