San Diego, CA (6/15/99)- Women
who do not want to take estrogen now have a variety of alternative treatments
to choose from for the prevention of osteoporosis associated with menopause,
reported researchers at the 81st Annual Meeting of the Endocrine
Society.
Estrogen
replacement therapy is an effective treatment for the symptoms of menopause,
such as hot flashes. However, its role in the prevention of osteoporosis is
not as well established. Moreover, many women cannot tolerate estrogen therapy
because of associated side effects or out of concern of cancer risk. Indeed,
up to 75% of women who are prescribed hormone replacement therapy discontinue
this treatment in less than one year.
The problematic status of estrogen
replacement therapy led to a rigorous search for alternative treatments for
osteoporosis. That search led to the development of several new treatment
approaches including the selective estrogen receptor modulators (SERMs) and
the nonhormonal biphosphonates.
"This is a time of considerable controversy
regarding the best approaches to the prevention and treatment of osteoporosis.
We have to remember that treatment and prevention are two different things.
Estrogen remains the best choice for the treatment of the symptoms of menopause.
The controversy centers on the best way to prevent the progressive bone loss
that accompanies menopause, without increasing the incidence of adverse effects,"
said Deborah Grady, MD, University of California, San Francisco, who compared
the pros and cons of hormone replacement, SERMs and biphosphonates in a comprehensive
review of randomized, placebo controlled clinical trials.
While the beneficial effects of hormone
replacement therapy on bone are taken for granted in some circles, the actual
clinical trial data are equivocal, Dr. Grady noted. Some clinical trials have
shown significant improvement in bone density and suggested a possible reduction
in the risk of cardiovascular disease. The more recent HERS (Heart and Estrogen-Progestin
Replacement Study) trial showed no difference in fracture rate in post-menopausal
women after four years of treatment with estrogen and progestin. IN addition,
women on hormone replacement therapy showed a 1.5-fold increased risk of coronary
events in the early years of follow-up. That risk decreased after 4 to 5 years.
"Why the discrepancy? It may be that
hormone replacement therapy really doesn't work. Or possibly, these patients
were not treated long enough to see a protective effect on bone. Or it may
be that the study enrolled patients who were not at high risk of fracture
to being with," said Dr. Grady, who was one of the chief investigators in
the HERS trial.
The SERM class of drugs was developed
in an attempt to retain the benefits of estrogen, while diminishing the risks.
Clinical trial data suggest that the fracture prevention potential for the
SERMs tamoxifen and raloxifene suggest is real but less substantial than that
of estrogen. While tamoxifen use was associated with significant reductions
in breast cancer risk during the first five years of a massive clinical study,
that protection did not last beyond five years. Moreover, tamoxifen, use,
like estrogen, is associated with an increased risk of endometrial cancer.
New data from the just released Multiple
Outcomes of Raloxifene Evaluation (MORE) study showed that the drug decreased
the risk of vertebral fractures, but not the risk of other types of fractures.
That study also showed a 76% reduction in the risk of breast cancer over a
three-year treatment period. Women receiving raloxifene in that study did
not show an increased incidence of endometrial cancer, but endometrial thickening
in some patients, suggests caution is in order, said Dr. Grady.
Nonhormonal agents may offer a better
risk/benefit ratio. Biphosphonate drugs restore the bone-building ability
of the body that is lost after menopause. Evidence from clinical trials with
the biphosphonate agent alendronate, indicate that the drug reduces fracture
risk by as much as 50% in post-menopausal women. The drug appears to be very
well tolerated, and is not associated with increased cardiovascular or cancer
risks. Another biphosphonate not yet approved in the US, risendronate appears
to produce similar results.
Novel Therapies
UCSF researchers reported promising
results with an entirely different approach to osteoporosis utilizing human
parathyroid hormone. The treatment restored bone mass to its original level
in nearly two thirds of the post-menopausal women participating in a randomized
double-blind placebo-controlled trial.
Men can also develop osteoporosis.
In another clinical trial, treatment with a testosterone patch for 36 months
increased bone mineral density in elderly men with low pretreatment serum
testosterone concentrations. The active treatment also increased lean tissue
mass and decreased fat mass. Another study of oral testosterone replacement
in healthy elderly men concluded that the therapy improved well-being sense,
muscle strength, joint pain and bone metabolism without changing lipid levels.
Phytoestrogens, plant-derived compounds
with hormone-like effects, are receiving increasing attention as a potential
treatment of osteoporosis and other components of menopause. Soy products
containing a type of phytoestrogen called isoflavones appear particularly
promising. A clinical trial conducted at the University of Cincinnati found
that adding soy products containing isoflavones to the diet produced significant
reductions in LDL ("bad" ) cholesterol. Positive effects were also seen on
bone. Another study using isoflavones derived from red clover showed marked
improvements in menopausal symptoms without altering lipid levels, sex hormones
or endometrial thickness.
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