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Study confirms that NSAIDs treatment
can reduce colorectal cancer risk
Safer drugs needed before regular
preventive therapy can be recommended
BOSTON - July 23, 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.
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 has not yet been 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."
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.
Media Contact: Sue
McGreevey, MGH Public Affairs
Physician Referral Service: 1-800-388-4644
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