Women who use estrogen after menopause
have lower death rates from all causes than those who do not, reports American
Cancer Society researchers, and this reduction in death is greatest for
coronary heart disease and for thinner women.
These findings, based on an analysis of data from the Society's landmark
Cancer Prevention Study II, is published in the January 15th edition of the
American Journal of Epidemiology.
Carmen Rodriguez, Ph.D. and colleagues from the American Cancer Society's
Epidemiology and Surveillance Research Department, responding to recent
evidence suggesting that the impact of estrogen use on disease outcomes may
vary by body mass, studied a group of 290,827 postmenopausal, primarily
elderly U.S. women. These women had no history of cancer or cardiovascular
disease when they were enrolled in the 1.2 million participant American Cancer
Society prospective study in l982.
After 12 years of follow-up, death rates from all causes among these women
were nearly 20% lower (Rate Ratio = 0.82) among estrogen users compared with
Estrogen users typically have healthier lifestyles and better
cardiovascular profiles than do non-users, which according to the researchers
may explain in part their lower death rates. However, the findings in this
analysis, say the authors, show a coronary heart disease rate that is larger
than would be explained by this "healthy user" bias.
The largest decrease in death rates was found in coronary heart disease
(CHD) and other circulatory diseases, (RR = 0.66 CHD, RR = 0.70, other
circulatory diseases). The rate ratio for CHD mortality associated with
estrogen use was significantly lower for the leanest women, those with a body
mass index (BMI) of less than 22. These women had a RR of 0.49. Body mass
index is a ratio of weight in pounds divided by height in inches squared. A
woman with BMI of less than 25 is considered thin or normal weight, between
25 and 30 is considered overweight, and BMI of 30 or more is considered
"Estrogen did not seem to lower the risk of dying from coronary heart
disease for women with a BMI of 30 or higher," reports Dr. Rodriguez.
"Overall, the risk of dying from coronary heart disease increases with greater
body mass index. Estrogen use decreases risk of dying from coronary heart
disease among thin and overweight women, but no impact was observed among
obese women" she observes.
The association of cancer mortality with estrogen use was found to be
minimal reports the study team. Cancer death rates were modestly lower among
estrogen users (RR = 0.91) and did not change overall in relation to BMI.
Some previous studies of women with established CHD have reported that the
use of estrogen did not protect against subsequent coronary disease events.
"Our findings do not conflict with findings from those studies," says
Dr. Rodriguez. "That's because we were looking at the hormone's effect on
women with no pre-existing heart disease.
"Our study does suggest that when a woman and her physician are in the
process of deciding for or against using hormone replacement at menopause,
body size should be another consideration in the estimation of potential risks
and benefits of the therapy," she added.
The American Cancer Society is the nationwide community-based voluntary
health organization dedicated to eliminating cancer as a major health problem
by preventing cancer, saving lives and diminishing suffering from cancer,
through research, education, advocacy and service.