Estrogen Can Help Bones, Studies Confirm

Two new studies confirm that taking hormones after menopause can strengthen women’s bones, perhaps heading off fractures in old age, researchers say.

However, a third study in today’s issue of the Journal of the American Medical Assn. found that older women with the strongest bones appear to have the highest risk of breast cancer. That finding may raise suspicions that estrogen supplements promote cancer, but outside experts quickly cautioned against that assumption.

Previous studies on the estrogen-breast cancer question yielded conflicting results and have suggested that any increased risk is slight.

“I would not recommend that women taking estrogen for osteoporosis even consider stopping their therapy,” said Dr. Karl Insogna, director of the Yale Bone Center in New Haven, Conn. He was not associated with any of the studies.

Insogna noted that estrogen is only one factor influencing bone density. “There are many other factors, such as exercise, race, calcium intake, other things that we don’t know,” he said.

Older women stop producing estrogen and take artificial hormones to counter symptoms of menopause such as hot flashes and vaginal dryness.

Estrogen encourages the uterus lining to thicken, as if it were to receive a fertilized egg, and progestins make the extra cells slough off if an egg doesn’t arrive. The sloughing off is important in preventing uterine cancer, which estrogen alone promotes.

In one of the studies on hormones and bones, post-menopausal women who took estrogen alone or with either of two types of progestins gained 5% bone mass in their spines and 1.7% in their hips over three years.

The women who took placebos lost an average of 1.8% of spinal bone mass and 1.7% of hip bone mass, said the researchers, led by epidemiologist Irma L. Mebane-Sims, who then worked for the National Heart, Lung and Blood Institute and now is an independent consultant.

In a second study, researchers tested an experimental combination of types of estrogen and progestin commonly used only in birth-control pills and it also proved successful in building bone mass, said researchers led by Dr. Leon Speroff of Oregon Health Sciences University.

The bone density/cancer study involved 6,854 women 65 and older, 97 of whom developed breast cancer over three years. Those women with the greatest bone mass had twice the breast-cancer risk of those with the least bone mass.