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Senior Citizen Health & Medicine
Senior Citizens Taking NSAIDS Like Aspirin Reduce
Risk of Colorectal Cancer
Safer drugs needed before regular therapy can be
recommended, researchers say
July 24, 2007 - A study of Medicare patients with
osteoarthritis provides additional evidence that non-steroidal
anti-inflammatory drugs (NSAIDs) such as aspirin reduce the risk of
colorectal cancer, at least for older people. The researchers, however,
quickly add that currently available NSAIDs should not be used solely to
prevent cancer.
Earlier investigations of the drugs’ impact on
tumor development could not rule out the possibility that an observed
protective effect was caused by other preventive health care measures.
The current study, led by a Massachusetts General Hospital (MGH)
physician, appears in the August 2007 Journal of General Internal
Medicine.
“This is good news for people who take NSAIDs
regularly for osteoarthritis,” says Elizabeth Lamont, MD, MS, of the MGH
Cancer Center, the study’s lead author.
“Although patients face risks such as bleeding or
kidney damage from this therapy, they probably are at a lower risk of
developing colorectal cancer.”
Because of the risks posed by the dosage used to
treat osteoarthritis, she and her co-authors stress that currently
available NSAIDs should not be used solely to prevent cancer.
Earlier randomized trials clearly showed that NSAID
treatment can prevent the development of precancerous colorectal polyps,
but whether or not such therapy also reduces the risk of invasive
colorectal cancer was not confirmed.
Those trials used relatively low doses of aspirin
and showed no significant differences in colorectal cancer rates between
the aspirin and placebo groups. While many observational studies have
shown a protective effect of NSAIDs against colorectal cancer,
interpretation of some of those results may have been clouded by other
healthy behaviors of the participants.
“It would be ideal to conduct a randomized clinical
trial – in which half the patients receive NSAIDs at doses higher than
those used in prior trials and half receive placebos – and follow both
groups for many years for evidence of cancer.
“But such trials are expensive, time consuming, and
could present real health risks to participants. Therefore, we took
advantage of a natural ‘experiment’ by comparing data from patients
known to regularly take higher amounts of NSAIDs with that from those
taking lower doses in order to evaluate any effect on colorectal cancer
risk.”
First the researchers reviewed data from the
1993-94 National Ambulatory Medical Care Survey, in which physicians
report on the diagnoses of and treatments prescribed to patients seen
during a randomly selected week.
Those results verified that older patients with
osteoarthritis were more than four times as likely to take NSAIDs as
were those without osteoarthritis.
They then analyzed information from the Survival
Epidemiology and End-Results (SEER)-Medicare program, studying groups of
elderly Medicare patients with and without colorectal cancer, to search
for associations with NSAID use.
Comparing information on 4,600 individuals with
colorectal cancer to data from 100,000 controls, they found that a
history of osteoarthritis was associated with a 15 percent reduction in
the likelihood of a colorectal cancer diagnosis. A similar association
was seen when total knee replacement was used as a marker for NSAID
treatment.
“The magnitude of colorectal cancer risk reduction
between patients with and without osteoarthritis is completely
consistent with the risk reduction for pre-cancerous polyps reported in
clinical trials of NSAIDs,” Lamont says.
“Confirming this association supports the need for
further research to identify NSAID agents safe enough to be used for
regular, preventive therapy by the general population.”
Editor’s Notes:
Lamont is an assistant professor of Medicine and
Health Care Policy at Harvard Medical School. Co-authors of this study,
which was supported by a grant from the National Cancer Institute, are
Lauren Dias, MD, North Shore Medical Center, and Diane Lauderdale, PhD,
University of Chicago.
Massachusetts General Hospital, established in
1811, is the original and largest teaching hospital of Harvard Medical
School. The MGH conducts the largest hospital-based research program in
the United States, with an annual research budget of more than $500
million and major research centers in AIDS, cardiovascular research,
cancer, computational and integrative biology, cutaneous biology, human
genetics, medical imaging, neurodegenerative disorders, regenerative
medicine, systems biology, transplantation biology and photomedicine.
MGH and Brigham and Women's Hospital are founding members of Partners
HealthCare HealthCare System, a Boston-based integrated health care
delivery system.
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