Low-Dose Estrogen Therapy Brings Benefits Without Increasing Risk
Endometrial hyperplasia is the overgrowth of tissue in the inner
lining of the uterus. It is non cancerous but can lead to excessive
uncontrollable bleeding and can be a precursor to endometrial
cancer. It normally effects women over the age of 35 and is thought
to be brought on by raised levels of estrogen.
But a recent study indicates that women are able to reap the
benefits of estrogen therapy, such as increased bone density
without increasing the risk of endometrial hyperplasia, as long as
the doses of estrogen given are low. The study, reported in the
Archives of Internal Medicine (157:2609-2615) involving 406
postmenopausal women found that a 0.3-mg does of estrified
estrogens resulted in positive bone and lipid changes without
inducing endometrial hyperplasia.
Each woman in the study was given 100 mg/d calcium and was
randomly assigned to receive continuous estrifed estrogens (0.3,
0.625, or 1.25 mg/d) or placebo for 24 months. All doses of
estrified estrogens produced significant increases in bone mineral
density of the lumbar spine compared with baseline and placebo.
Clinically relevant rates of endometrial hyperplasia were noted only
in groups receiving 0.625 and 1.25 mg of estrified estrogens daily.
The study has identified what seems to be a point of balance
between risk and benefit. Normally the increased risk of
endometrial hyperplasia with hormone replacement therapy has
been managed by prescribing a combination of estrogen and
progesterone. The logic behind this course of treatment is that this
combination stimulates menstruation, which decreases the risk of
endometrial cancer by stimulating the body to regularly shed the
endometrium. If the endometrium is not shed, any division of cells
(cancer) will remain in the uterus rather than getting flushed out.
What this study tells us is that there might be another option, where
the levels of estrogen used are low enough that cell division is not
stimulated and so there is no need for induced menstruation, but
the levels are high enough to increase bone density.