Here's more on ERT and colon cancer prevention:
Thursday April 30 7:08 PM EDT
Hormone Replacement Cuts Colon Cancer Risk
WESTPORT (Reuters) -- Hormone replacement therapy (HRT) can reduce the risk of colorectal cancer, but aspirin appears
to have no protective effect, according to the results of two large studies published in the May 1st issue of Annals of Internal
Medicine.
Several observational studies have indicated that regular aspirin use may reduce the risk of colorectal cancer. However,
12-year follow-up data from over 22,000 participants in the Physicians' Health Study do not corroborate such reports,
according to Dr. Til Sturmer of the University of Ulm in Germany and a multicenter German and American team.
Twelve years after randomization to 325 milligrams of aspirin per day or placebo, the relative risk of colorectal cancer in
patients assigned to aspirin was 1.03, indicating no protective effect of aspirin. And when the investigators looked specifically at
men who continued to take aspirin regularly after the randomized aspirin trial was stopped in 1988, they found that the relative
risk of colorectal cancer in continued aspirin users increased slightly to 1.07.
Sturmer and colleagues believe that their "...findings indicate that a causal role of aspirin in the prevention of colorectal cancer is
less likely..." than previously thought.
Meanwhile, researchers in Boston, Massachusetts, and Tucson, Arizona, show that women taking postmenopausal HRT may
have a substantially lower risk of colorectal cancer compared with those not taking HRT, according to findings from the
Nurses' Health Study.
Lead author Dr. Francine Grodstein of Channing Laboratory in Boston, and others found that women currently using HRT had
a relative risk of developing colorectal cancer of 0.65, indicating a 35% reduction in risk relative to nonusers or never-users.
The duration of hormone use did not significantly affect the risk of colorectal cancer, the researchers report, but the protective
effect of HRT appeared to diminish after discontinuation of the therapy, disappearing completely after 5 years of nonuse.
The Nurses' Health Study findings are "...consistent with substantial epidemiologic and biological data," Grodstein and
colleagues write. Based on this study, they calculate that "...30 cases of colorectal cancer would be prevented per 100,000
person-years of hormone use among women 55 to 59 years of age." And the benefits of HRT would likely increase as women
age and enter older age-groups at increased risk of colorectal cancer.
The Boston and Tucson team stress that the potential for HRT to protect women against colorectal cancer must be weighed
along with its other benefits, such as protection against osteoporosis and cardiovascular disease, and risks, including an increase
in breast cancer risk.
Dr. Robert N. Hoover of the National Cancer Institute (NCI) in Bethesda, Maryland, in a related editorial entitled, "Cancer
Prevention: Better Late than Never?" comments that the Nurses' Health Study findings provide one more example of how
"...'late' exposures may influence cancer risk and... (add) to the enthusiasm for interventions that may result in rapid risk
reduction."
According to the NCI researcher, more study is needed before adding colorectal cancer prevention to the list of indications for
HRT. SOURCE: Annals of Internal Medicine (1998;128:705-712, 713-720, 771-772)
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